Document performance changes and measured results

build.ts

@@ -10,8 +10,9 @@ const result = await Bun.build({
   outdir,
   plugins: [tailwind],
   minify: true,
+  splitting: true,
   target: "bun",
-  external: ["@napi-rs/canvas"],
+  external: ["@napi-rs/canvas", "/fonts/browser/*"],
   sourcemap: "linked",
   define: {
     "process.env.NODE_ENV": JSON.stringify("production"),
@@ -30,3 +31,8 @@ await mkdir(path.join(outdir, "fonts"), { recursive: true });
 for (const file of ["InstrumentSerif-Regular.ttf", "NotoSans-Regular.ttf", "NotoSans-Medium.ttf", "NotoSans-SemiBold.ttf"]) {
   await copyFile(`src/assets/fonts/${file}`, path.join(outdir, "fonts", file));
 }
+
+await mkdir(path.join(outdir, "fonts/browser"), { recursive: true });
+for (const file of ["InstrumentSerif-Regular", "InstrumentSerif-Italic", "NotoSans-Regular", "NotoSans-Medium", "NotoSans-SemiBold"]) {
+  await copyFile(`src/assets/fonts/${file}.woff2`, path.join(outdir, `fonts/browser/${file}.woff2`));
+}

bunfig.toml

@@ -3,5 +3,5 @@
 env = false
 
 [serve.static]
-plugins = ["bun-plugin-tailwind"]
+plugins = ["bun-plugin-tailwind", "./scripts/browser-fonts-plugin.ts"]
 env = "BUN_PUBLIC_*"

docs/performance.md

@@ -0,0 +1,66 @@
+# Performance improvements
+
+The September 2026 audit produced twelve changes, implemented in separate backend,
+frontend, and worker worktrees and verified together before release.
+
+## Changes
+
+| Area | Improvement |
+| --- | --- |
+| Database reads | Fetch the latest day snapshots, tasks, and effective revisions for the requested dates. Carry-enabled counts look back to the necessary prior reset or log. |
+| Synchronization | Skip already-materialized habits and unchanged marker writes; expire tasks using an index of open occurrences. |
+| Catch-up | Materialize bounded batches with bulk task inserts, yield between batches, and serialize same-account operations until their data is ready. |
+| Calendar payloads | `compact=true` omits task lists and repeated requirements. Dated editing endpoints retain full detail. |
+| Calendar caching | Cache account-scoped ranges using persisted per-habit change versions; fetch visible months first and extend on demand. Historical edits and local midnight invalidate the appropriate data. |
+| React rendering | Preserve unchanged habit objects and callbacks; memoize calendar data and geometry. |
+| Initial JavaScript | Split the showcase and optional forms, editors, settings, and sharing interfaces into lazy-loaded modules. |
+| Browser fonts | Serve complete WOFF2 fonts separately with conditional caching; retain the original TTF files for native image rendering. |
+| Image rendering | Share a bounded queue across server renderers, deduplicate identical in-flight requests within their owner, and release completed canvas surfaces. |
+| Backups | Run SQLite snapshots, verification, durability, and replication in a subprocess, preserving startup health and overlap prevention. |
+| Reminders | Check delivery-slot eligibility before evaluating habits; revalidate preferences and progress immediately before sending. |
+| Avatars | Bound cached images/downloads, reuse concurrent downloads, and briefly cache failures. |
+
+## Local measurements
+
+These are synthetic measurements on a development Mac, not production capacity
+estimates. Absolute timings vary with hardware and load.
+
+| Scenario | Before | After |
+| --- | ---: | ---: |
+| Dashboard service work, ten task habits with five years of history | 169.81 ms | 2.76 ms |
+| Unchanged synchronization, ten habits | 34 queries / 10 row changes | 4 queries / 0 row changes |
+| Combined year calendar, ten habits with ten tasks each | 10,693,864 JSON bytes | 1,267,884 compact JSON bytes |
+| Catching up a year, ten habits with ten tasks each | ~1.17 s without yielding | ~1.11 s total; 112 timer ticks, largest gap 11.75 ms |
+| Initial calendars, ten new manual habits | 1,947,301 JSON characters | 476,954 JSON characters |
+| Unchanged focus refresh, same ten habits | 11 requests / 10 calendar requests | 1 request / 0 calendar requests |
+| Switching identical habit filters | 920 `Date.parse` calls | 0 |
+| Initial JavaScript, including static dependencies | 716,094 bytes | 286,641 bytes |
+| Initial JavaScript, locally gzip-compressed | 199,622 bytes | 99,192 bytes |
+| Main stylesheet | 273,268 bytes | 85,733 bytes |
+| Main stylesheet, locally gzip-compressed | 106,410 bytes | 13,636 bytes |
+| Fifty already-delivered reminder checks | 210 ms / 1,000 day evaluations | 14 ms / 0 day evaluations |
+| Three renders with the same avatar URL | 3 downloads | 1 download |
+| Sixteen identical concurrent image renders: timer delay | 68 ms | 1.1 ms |
+| ~98 MiB replicated backup: main-thread timer delay | 421 ms | 1.9 ms |
+
+Calendar byte/character counts describe serialized JSON, not compressed wire
+traffic. JavaScript/CSS gzip sizes are local compression estimates. Image RSS
+measurements concern transient native allocations, not memory leaks.
+
+## Operation and verification
+
+The application remains one Bun process with SQLite/WAL and one set of Discord
+delivery workers. The backup subprocess owns a separate connection. Render
+admission defaults to two active jobs, sixteen total pending jobs, and two jobs
+per account; an overloaded renderer returns a retryable busy response.
+
+Migrations add a persisted calendar revision and a partial index for open task
+occurrences. Existing historical requirements, carryover rules, privacy boundaries,
+rate-limit handling, and confirmed-deleted-message replacement remain covered by
+regression tests.
+
+Run `bun run typecheck`, `bun test`, and `bun run test:smoke`. The smoke test uses
+a disposable production database. Browser verification should cover lazy route
+and dialog loading, count/task saves, historical corrections, calendar ranges,
+both themes, narrow layouts, and separately served fonts. Timing tests should
+measure event-loop availability as well as total job duration.

drizzle/0013_habit_calendar_revision.sql

@@ -0,0 +1 @@
+ALTER TABLE habits ADD COLUMN calendar_revision integer NOT NULL DEFAULT 0;

drizzle/0014_open_occurrences.sql

@@ -0,0 +1 @@
+CREATE INDEX task_occurrences_open_idx ON task_occurrences (day_id) WHERE closed_at IS NULL;

drizzle/meta/_journal.json

@@ -92,6 +92,20 @@
       "when": 1788847978168,
       "tag": "0012_discord_commands",
       "breakpoints": true
+    },
+    {
+      "idx": 13,
+      "version": "6",
+      "when": 1788860000000,
+      "tag": "0013_habit_calendar_revision",
+      "breakpoints": true
+    },
+    {
+      "idx": 14,
+      "version": "6",
+      "when": 1788860000001,
+      "tag": "0014_open_occurrences",
+      "breakpoints": true
     }
   ]
 }

scripts/backup.ts

@@ -1,5 +1,7 @@
 import { Database } from "bun:sqlite";
 import { databasePath } from "../src/db/config";
 import { backupConfig, createBackup } from "../src/ops/backups";
-const db = new Database(databasePath, { readonly: true, strict: true });
+// SQLite needs writable WAL bookkeeping when the first snapshot opens a cold database.
+// Only snapshot SQL runs here; never create a missing source file.
+const db = new Database(databasePath, { readwrite: true, create: false, strict: true });
 try { console.log(createBackup(db, backupConfig(databasePath))); } finally { db.close(); }

scripts/browser-fonts-plugin.ts

@@ -0,0 +1,9 @@
+import type { BunPlugin } from "bun";
+
+/** Match the production bundler's external font URLs in the HTML dev server. */
+export default {
+  name: "external-browser-fonts",
+  setup(build) {
+    build.onResolve({ filter: /^\/fonts\/browser\// }, args => ({ path: args.path, external: true }));
+  },
+} satisfies BunPlugin;

scripts/dashboard-preview.ts

@@ -1,3 +1,4 @@
+import { browserFont } from "../src/browser-fonts";
 // Isolated browser QA server. Never opens or changes the user's database.
 import { sendDueReminders } from "../src/reminders/worker";
 import type { DiscordFetch } from "../src/sharing/routes";
@@ -55,6 +56,7 @@ const server = Bun.serve({
   hostname: "127.0.0.1",
   port,
   routes: {
+    "/fonts/browser/*": browserFont,
     "/__preview/reminder": () => new Response(reminderMessage ?? "No reminder sent"),
     "/__preview/shared-image": () => sharingPreview && sharedImage ? new Response(sharedImage) : new Response(null, { status: 404 }),
     "/__preview/login": () =>

scripts/scheduled-backup.ts

@@ -0,0 +1,18 @@
+import { Database } from 'bun:sqlite';
+import { createBackup, latestBackupTime, type BackupConfig } from '../src/ops/backups';
+
+const path = process.argv[2];
+if (!path || !process.argv[3]) throw new Error('Expected database path and backup configuration');
+const config = JSON.parse(process.argv[3]) as BackupConfig;
+const latest = latestBackupTime(config);
+if (latest && Date.now() - latest < config.intervalMs) console.log(JSON.stringify({ timestamp: latest, created: false }));
+else {
+  // SQLite needs writable WAL bookkeeping when the first snapshot opens a cold database.
+  // Only snapshot SQL runs here; never create a missing source file.
+  const db = new Database(path, { readwrite: true, create: false, strict: true });
+  try {
+    db.exec('PRAGMA busy_timeout=5000');
+    createBackup(db, config);
+    console.log(JSON.stringify({ timestamp: latestBackupTime(config), created: true }));
+  } finally { db.close(); }
+}

src/App.test.tsx

@@ -91,6 +91,12 @@ function LocationProbe() {
   </>;
 }
 
+async function settleDeferred() {
+  for (let attempt = 0; attempt < 100 && [...container.querySelectorAll('[role="status"]')].some(node => node.textContent === "Loading…"); attempt++) {
+    await act(async () => { await new Promise(resolve => setTimeout(resolve, 1)); });
+  }
+}
+
 async function render(path = "/design-system") {
   await act(async () =>
     root.render(
@@ -100,6 +106,7 @@ async function render(path = "/design-system") {
       </MemoryRouter>,
     ),
   );
+  await settleDeferred();
 }
 
 function connectAccount() {
@@ -131,6 +138,7 @@ describe("homepage", () => {
     const opener = buttonNamed("Settings");
     opener.focus();
     await act(async () => opener.click());
+    await settleDeferred();
     const dialog = container.querySelector<HTMLDialogElement>("dialog#account-settings")!;
     expect(dialog.open).toBe(true);
     expect(dialog.contains(document.activeElement)).toBe(true);
@@ -158,6 +166,7 @@ describe("homepage", () => {
     expect(inner.open).toBe(true);
     expect(inner.querySelector<HTMLButtonElement>('[aria-label="Close dialog"]')?.disabled).toBe(true);
     await act(async () => buttonNamed("Finish save").click());
+    await settleDeferred();
     await act(async () => inner.dispatchEvent(new dom.Event("cancel", { cancelable: true }) as unknown as Event));
     expect(container.querySelector("#inner")).toBeNull();
     expect(container.querySelector<HTMLDialogElement>("#outer")?.open).toBe(true);
@@ -175,10 +184,13 @@ describe("homepage", () => {
     await f.request(`/habits/${h.id}`, "DELETE");
     await render("/");
     await act(async () => buttonNamed("Archived habits").click());
+    await settleDeferred();
     expect(buttonNamed("Restore Reading")).toBeDefined();
     await act(async () => buttonNamed("View history").click());
+    await settleDeferred();
     expect(container.querySelector('[aria-label="2026-09-03: 1 of 1 completion · Complete"]')).not.toBeNull();
     await act(async () => buttonNamed("Restore Reading").click());
+    await settleDeferred();
     expect(container.textContent).toContain("No archived habits.");
     expect((await f.json("/today")).habits[0].name).toBe("Reading");
     expect((await f.json(`/habits/${h.id}/days/2026-09-03`)).complete).toBe(true);
@@ -190,12 +202,16 @@ describe("homepage", () => {
     await f.request(`/habits/${habit.id}`, "DELETE");
     await render("/");
     await act(async () => buttonNamed("Archived habits").click());
+    await settleDeferred();
     await act(async () => buttonNamed("Delete permanently Discard me").click());
+    await settleDeferred();
     expect(container.querySelector("#delete-archived-habit")?.textContent).toContain("This cannot be undone.");
     expect(document.activeElement).toBe(buttonNamed("Keep habit"));
     await act(async () => buttonNamed("Keep habit").click());
+    await settleDeferred();
     expect((await f.request(`/habits/${habit.id}`)).status).toBe(200);
     await act(async () => buttonNamed("Delete permanently Discard me").click());
+    await settleDeferred();
     const confirm = () => container.querySelector<HTMLButtonElement>("#delete-archived-habit .ds-action-row button:last-child")!;
     fetchMock.mockResolvedValueOnce(Response.json({ error: "Temporary failure" }, { status: 500 }));
     await act(async () => confirm().click());
@@ -210,7 +226,7 @@ describe("homepage", () => {
 
   test("historical check-ins use the selected date's tracking method and preserve today", async () => {
     const f = connectAccount();
-    f.setTime("2026-09-03T12:00:00Z");
+    f.setTime("2026-01-03T12:00:00Z");
     const habit = await f.json("/habits", "POST", { name: "Reading", method: "manual" }, 201);
     f.setTime("2026-09-04T12:00:00Z");
     await f.json(`/habits/${habit.id}`, "PATCH", { method: "count", target: 10, unit: "pages" });
@@ -220,12 +236,21 @@ describe("homepage", () => {
     await act(async () => container.querySelector<HTMLButtonElement>('[aria-label^="2026-09-03:"]')!.click());
     expect(buttonNamed("Edit selected check-in").closest(".ds-date-inspector")?.textContent).toContain("September 3, 2026");
     await act(async () => buttonNamed("Edit selected check-in").click());
+    await settleDeferred();
     const past = [...container.querySelectorAll<HTMLInputElement>('input[type="checkbox"]')].find(input => input.closest("label")?.textContent === "Completed on this date")!;
     expect(past).toBeDefined();
     await act(async () => past.click());
     expect((await f.json(`/habits/${habit.id}/days/2026-09-03`)).complete).toBe(true);
     expect((await f.json(`/habits/${habit.id}/days/2026-09-04`)).value).toBe(0);
     expect(container.textContent).toContain("Saved check-in for 2026-09-03");
+    fetchMock.mockClear();
+    await act(async () => {
+      const input = container.querySelector<HTMLInputElement>('input[type="date"]')!;
+      Object.getOwnPropertyDescriptor(dom.HTMLInputElement.prototype, "value")!.set!.call(input, "2026-01-03");
+      input.dispatchEvent(new dom.Event("change", { bubbles: true }) as unknown as Event);
+    });
+    expect(container.querySelector('[aria-label^="2026-01-03:"]')).not.toBeNull();
+    expect(fetchMock.mock.calls.some(([url]) => String(url).includes("from=2025-11-01") && String(url).includes("compact=true"))).toBe(true);
   });
 
   test("signed-out visitors can try progress without calling private habit APIs", async () => {
@@ -233,6 +258,7 @@ describe("homepage", () => {
     expect(container.querySelector("h1")?.textContent).toBe("Small steps.Lasting rhythm.");
     expect(fetchMock.mock.calls.map(call => call[0])).toEqual(["/api/me"]);
     await act(async () => buttonNamed("Increase glasses of water").click());
+    await settleDeferred();
     expect(container.querySelector<HTMLInputElement>('[aria-label="Total glasses of water"]')?.value).toBe("4");
     expect(fetchMock).toHaveBeenCalledTimes(1);
   });
@@ -264,6 +290,7 @@ describe("homepage", () => {
     expect(container.textContent).toContain("Account unavailable");
     expect(container.querySelector("#welcome-title")).toBeNull();
     await act(async () => buttonNamed("Try again").click());
+    await settleDeferred();
     expect(container.querySelector("#welcome-title")).not.toBeNull();
   });
 
@@ -273,6 +300,7 @@ describe("homepage", () => {
     expect(container.textContent).toContain("Welcome back, alice.");
     expect(container.textContent).toContain("Start with one habit.");
     await act(async () => buttonNamed("Add a habit +").click());
+    await settleDeferred();
     const input = container.querySelector<HTMLInputElement>("form input")!;
     expect(document.activeElement).toBe(input);
     await act(async () => {
@@ -285,6 +313,7 @@ describe("homepage", () => {
     expect(container.textContent).not.toContain("Read a little created.");
     expect(container.querySelector(".ds-habit-chart")).not.toBeNull();
     await act(async () => buttonNamed("Sign out").click());
+    await settleDeferred();
     expect(container.querySelector("#welcome-title")).not.toBeNull();
     expect((await f.request("/me")).status).toBe(401);
   });
@@ -310,12 +339,14 @@ describe("homepage", () => {
     expect(container.querySelectorAll('.ds-goal--tasks .ds-routine-items > li')).toHaveLength(1);
 
     await act(async () => buttonNamed("Increase Water").click());
+    await settleDeferred();
     expect(container.querySelector(".ds-welcome-progress")?.textContent).toContain("1 / 3");
     expect(container.querySelectorAll(".ds-goal-graph .ds-calendar")).toHaveLength(3);
     expect(countGoal.querySelector(".ds-goal-status")?.textContent).toBe("Complete");
     expect(container.querySelector(`#history-${water.id} .ds-date-inspector`)?.textContent).toContain("8 of 8 glasses");
     expect(container.textContent).not.toContain("Sunday walk");
     await act(async () => buttonNamed("All habits · 4").click());
+    await settleDeferred();
     const checkbox = (name: string) => [...container.querySelectorAll<HTMLInputElement>('input[type="checkbox"]')].find(input => (input.getAttribute("aria-label") || input.closest("label")?.textContent) === name)!;
     expect(checkbox("Sunday walk done").disabled).toBe(true);
     await act(async () => checkbox("Reading done").click());
@@ -323,9 +354,81 @@ describe("homepage", () => {
     expect(container.querySelector(".ds-welcome-progress")?.textContent).toContain("3 / 3");
     expect((await f.json("/today")).completed).toBe(3);
     await act(async () => buttonNamed("Decrease Water").click());
+    await settleDeferred();
     expect((await f.json("/today")).completed).toBe(2);
   });
 
+  test("focus retains unchanged calendars, detects remote historical edits and loads expanded history on demand", async () => {
+    const f = connectAccount();
+    f.setTime("2026-09-03T12:00:00Z");
+    const reading = await f.json("/habits", "POST", { name: "Reading", method: "manual" }, 201);
+    await f.json("/habits", "POST", { name: "Walking", method: "manual" }, 201);
+    f.setTime("2026-09-04T12:00:00Z");
+    await render("/");
+    const calendarRequests = () => fetchMock.mock.calls.map(([url]) => String(url)).filter(url => url.includes("/calendar?"));
+    expect(calendarRequests()).toHaveLength(2);
+    expect(calendarRequests()[0]).toContain("from=2026-07-01");
+    expect(calendarRequests()[0]).toContain("compact=true");
+    const parse = spyOn(Date, "parse");
+    await act(async () => buttonNamed("All habits · 2").click());
+    await settleDeferred();
+    expect(parse).not.toHaveBeenCalled();
+    parse.mockRestore();
+    fetchMock.mockClear();
+    await act(async () => dom.dispatchEvent(new dom.Event("focus")));
+    expect(calendarRequests()).toHaveLength(0);
+    await f.json(`/habits/${reading.id}/days/2026-09-03/progress`, "PUT", { done: true });
+    await act(async () => dom.dispatchEvent(new dom.Event("focus")));
+    expect(calendarRequests()).toHaveLength(1);
+    expect(calendarRequests()[0]).toContain(reading.id);
+    const history = container.querySelector(`#history-${reading.id}`)!;
+    fetchMock.mockClear();
+    await act(async () => history.querySelector<HTMLButtonElement>('[aria-label="12 months"]')!.click());
+    expect(calendarRequests()).toHaveLength(1);
+    expect(calendarRequests()[0]).toContain("from=2025-10-01");
+    expect(history.querySelectorAll(".ds-day")).toHaveLength(365);
+    fetchMock.mockClear();
+    await act(async () => history.querySelector<HTMLButtonElement>('[aria-label="3 months"]')!.click());
+    expect(calendarRequests()).toHaveLength(0);
+    expect(history.querySelectorAll(".ds-day")).toHaveLength(92);
+    expect(history.querySelector('[aria-label="2026-09-03: 1 of 1 completion · Complete"]')).not.toBeNull();
+    fetchMock.mockClear();
+    f.setTime("2026-09-05T12:00:00Z");
+    await act(async () => dom.dispatchEvent(new dom.Event("focus")));
+    expect(calendarRequests()).toHaveLength(2);
+  });
+
+  test("month rollover preserves a twelve-month preset and an explicit custom window", async () => {
+    const f = connectAccount();
+    f.setTime("2026-09-30T12:00:00Z");
+    const annual = await f.json("/habits", "POST", { name: "Annual", method: "manual" }, 201);
+    const custom = await f.json("/habits", "POST", { name: "Custom", method: "manual" }, 201);
+    await render("/");
+    const annualHistory = container.querySelector(`#history-${annual.id}`)!;
+    const customHistory = container.querySelector(`#history-${custom.id}`)!;
+    await act(async () => annualHistory.querySelector<HTMLButtonElement>('[aria-label="12 months"]')!.click());
+    await act(async () => [...customHistory.querySelectorAll<HTMLButtonElement>("button")].find(button => button.textContent === "Custom")!.click());
+    await act(async () => {
+      for (const [name, value] of [["from", "2026-08-05"], ["to", "2026-09-10"]]) {
+        const input = customHistory.querySelector<HTMLInputElement>(`input[name="${name}"]`)!;
+        Object.getOwnPropertyDescriptor(dom.HTMLInputElement.prototype, "value")!.set!.call(input, value);
+        input.dispatchEvent(new dom.Event("change", { bubbles: true }) as unknown as Event);
+      }
+      customHistory.querySelector("form")!.dispatchEvent(new dom.Event("submit", { bubbles: true, cancelable: true }) as unknown as Event);
+    });
+    fetchMock.mockClear();
+    f.setTime("2026-10-01T12:00:00Z");
+    await act(async () => dom.dispatchEvent(new dom.Event("focus")));
+    const requests = fetchMock.mock.calls.map(([url]) => String(url)).filter(url => url.includes("/calendar?"));
+    expect(requests).toHaveLength(2);
+    expect(requests.find(url => url.includes(annual.id))).toContain("from=2025-11-01&to=2026-10-31");
+    expect(requests.find(url => url.includes(custom.id))).toContain("from=2026-08-05&to=2026-09-10");
+    expect(annualHistory.querySelector(".ds-calendar")?.getAttribute("data-months")).toBe("12");
+    expect(annualHistory.querySelectorAll(".ds-day")).toHaveLength(365);
+    expect(customHistory.querySelector(".ds-calendar")?.getAttribute("data-months")).toBe("custom");
+    expect(customHistory.querySelectorAll(".ds-day")).toHaveLength(37);
+  });
+
   test("a pending counter save leaves other habits usable and refreshes only its history", async () => {
     const f = connectAccount();
     const water = await f.json("/habits", "POST", { name: "Water", method: "count", target: 8, unit: "glasses" }, 201);
@@ -341,6 +444,7 @@ describe("homepage", () => {
     }, { preconnect: fetch.preconnect }));
     fetchMock.mockClear();
     await act(async () => buttonNamed("Increase Water").click());
+    await settleDeferred();
     expect(buttonNamed("Increase Water").disabled).toBe(true);
     const check = container.querySelector<HTMLInputElement>('[aria-label="Reading done"]')!;
     expect(check.disabled).toBe(false);
@@ -367,6 +471,7 @@ describe("homepage", () => {
     f.setTime("2026-09-04T12:00:00Z");
     await render("/");
     await act(async () => buttonNamed("Edit habit Water").click());
+    await settleDeferred();
     const form = container.querySelector<HTMLFormElement>('form[aria-label="Edit habit Water"]')!;
     expect(document.activeElement).toBe(form.querySelector("input"));
     await act(async () => {
@@ -384,11 +489,15 @@ describe("homepage", () => {
     expect(container.querySelector("form")).toBeNull();
     expect(container.querySelector("h3")?.textContent).toContain("Daily water");
     await act(async () => buttonNamed("Archive habit Daily water").click());
+    await settleDeferred();
     expect((await f.json("/habits")).habits).toHaveLength(1);
     await act(async () => buttonNamed("Cancel").click());
+    await settleDeferred();
     expect((await f.json("/habits")).habits).toHaveLength(1);
     await act(async () => buttonNamed("Archive habit Daily water").click());
+    await settleDeferred();
     await act(async () => buttonNamed("Archive habit").click());
+    await settleDeferred();
     expect((await f.json("/habits")).habits).toHaveLength(0);
     expect(container.querySelector(".ds-habit-chart")).toBeNull();
     const previous = await f.json(`/habits/${habit.id}/days/2026-09-03`);
@@ -407,6 +516,7 @@ describe("homepage", () => {
     await f.json(`/habits/${habit.id}/days/2026-09-04/tasks/${task.id}`, "PUT", { done: true });
     await render("/");
     await act(async () => buttonNamed("Edit task Stretch").click());
+    await settleDeferred();
     const form = container.querySelector<HTMLFormElement>('form[aria-label="Edit task Stretch"]')!;
     await act(async () => {
       const input = form.querySelector("input")!;
@@ -419,7 +529,9 @@ describe("homepage", () => {
     expect(saved.schedule).toEqual({ type: "weekdays", days: [4, 5] });
     expect((await f.json("/today")).habits[0].value).toBe(1);
     await act(async () => buttonNamed("Delete task Stretch gently").click());
+    await settleDeferred();
     await act(async () => buttonNamed("Delete task").click());
+    await settleDeferred();
     const today = (await f.json("/today")).habits[0];
     expect(today.target).toBe(1);
     expect(today.value).toBe(0);
@@ -435,9 +547,11 @@ describe("homepage", () => {
     await render("/");
     expect(container.querySelector(".ds-habit-chart")).toBeNull();
     await act(async () => buttonNamed("All habits · 1").click());
+    await settleDeferred();
     expect(container.textContent).toContain("Not scheduled today");
     expect(container.querySelector<HTMLInputElement>('.ds-editable-task input[type="checkbox"]')?.disabled).toBe(true);
     await act(async () => buttonNamed("Edit task Walk").click());
+    await settleDeferred();
     const form = container.querySelector<HTMLFormElement>('form[aria-label="Edit task Walk"]')!;
     await act(async () => {
       const input = form.querySelector("input")!;
@@ -477,6 +591,7 @@ describe("homepage", () => {
       { type: "daily" },
     ] as const) {
       await act(async () => buttonNamed("Edit task Walk").click());
+    await settleDeferred();
       const form = container.querySelector<HTMLFormElement>('form[aria-label="Edit task Walk"]')!;
       await selectValue(form.querySelector("select")!, schedule.type);
       if (schedule.type === "interval" || schedule.type === "weekly") {
@@ -489,6 +604,7 @@ describe("homepage", () => {
       if (schedule.type === "interval") expect(buttonNamed("All habits · 1").getAttribute("aria-pressed")).toBe("true");
       expect(container.querySelector("form")).toBeNull();
       await act(async () => buttonNamed("Edit task Walk").click());
+    await settleDeferred();
       const reopened = container.querySelector<HTMLFormElement>('form[aria-label="Edit task Walk"]')!;
       expect(reopened.querySelector("select")?.value).toBe(schedule.type);
       if (schedule.type === "interval" || schedule.type === "weekly") {
@@ -496,6 +612,7 @@ describe("homepage", () => {
         expect(reopened.querySelector<HTMLInputElement>('input[type="date"]')?.value).toBe(schedule.anchor);
       }
       await act(async () => buttonNamed("Cancel").click());
+    await settleDeferred();
     }
     const previous = await f.json(`/habits/${habit.id}/days/2026-09-03`);
     expect(previous.tasks[0].done).toBe(true);
@@ -515,17 +632,20 @@ describe("homepage", () => {
     };
     const submit = async () => act(async () => container.querySelector("form")!.dispatchEvent(new dom.Event("submit", { bubbles: true, cancelable: true }) as unknown as Event));
     await act(async () => buttonNamed("Edit habit Reading").click());
+    await settleDeferred();
     await selectMethod("count");
     await act(async () => container.querySelector<HTMLInputElement>('form input[type="checkbox"]')!.click());
     await submit();
     expect((await f.json(`/habits/${habit.id}`)).method).toBe("count");
     expect((await f.json(`/habits/${habit.id}`)).carryPartialProgress).toBe(true);
     await act(async () => buttonNamed("Edit habit Reading").click());
+    await settleDeferred();
     expect(container.querySelector<HTMLInputElement>('form input[type="checkbox"]')?.checked).toBe(true);
     await selectMethod("tasks");
     await submit();
     expect((await f.json(`/habits/${habit.id}`)).method).toBe("tasks");
     await act(async () => buttonNamed("Add task").click());
+    await settleDeferred();
     const form = container.querySelector<HTMLFormElement>('form[aria-label="Add task"]')!;
     await act(async () => {
       const input = form.querySelector("input")!;
@@ -545,16 +665,19 @@ describe("homepage", () => {
     const habit = await f.json("/habits", "POST", { name: "Reading", method: "manual" }, 201);
     await render("/");
     await act(async () => buttonNamed("Archive habit Reading").click());
+    await settleDeferred();
     fetchMock.mockImplementationOnce((async (input, init) => {
       return f.request(String(input).replace("/api", ""), init?.method);
     }) as typeof fetch);
     fetchMock.mockResolvedValueOnce(new Response(null, { status: 500 }));
     await act(async () => buttonNamed("Archive habit").click());
+    await settleDeferred();
     expect(container.querySelector("form")).toBeNull();
     expect(container.textContent).toContain("Your change was saved, but the dashboard could not refresh");
     expect(buttonNamed("Archive habit Reading").disabled).toBe(true);
     expect((await f.json(`/habits/${habit.id}`)).archived).toBe(true);
     await act(async () => buttonNamed("Try again").click());
+    await settleDeferred();
     expect(container.querySelector(".ds-habit-chart")).toBeNull();
     expect(fetchMock.mock.calls.filter(call => call[1]?.method === "DELETE")).toHaveLength(1);
   });
@@ -565,10 +688,12 @@ describe("homepage", () => {
     await render("/");
     fetchMock.mockResolvedValueOnce(Response.json({ error: "Save unavailable" }, { status: 500 }));
     await act(async () => buttonNamed("Increase Water").click());
+    await settleDeferred();
     expect(container.querySelector('[role="alert"]')?.textContent).toContain("Save unavailable");
     expect(container.querySelector<HTMLInputElement>('[aria-label="Total Water"]')?.value).toBe("0");
     expect(buttonNamed("Increase Water").disabled).toBe(false);
     await act(async () => buttonNamed("Increase Water").click());
+    await settleDeferred();
     expect(container.querySelector<HTMLInputElement>('[aria-label="Total Water"]')?.value).toBe("1");
     expect((await f.json("/today")).habits[0].value).toBe(1);
   });

src/App.tsx

@@ -1,5 +1,6 @@
 import { Navigate, Route, Routes } from "react-router";
-import { DesignSystem } from "./pages/DesignSystem";
+import { deferred } from "./components/design-system/deferred";
+const DesignSystem = deferred(() => import("./pages/DesignSystem").then(module => module.DesignSystem));
 import { Home } from "./pages/Home";
 import { AuthProvider } from "./components/AuthProvider";
 

src/account/routes.ts

@@ -8,9 +8,8 @@ import { HabitService } from "../habits/service";
 export function createAccountRoutes(db: AppDatabase, auth: ReturnType<typeof createAuth>, now: () => number) {
   const app = new Hono<AuthEnv>();
   app.use("*", auth.requireAuth);
-  app.get("/export", c => {
+  app.get("/export", c => HabitService.withPrepared(db, c.get("user"), now, () => {
     const user = c.get("user");
-    const service = new HabitService(db, user, now()); service.sync();
     const data = db.transaction(tx => {
       const owned = tx.select({ id: schema.habits.id }).from(schema.habits).where(eq(schema.habits.userId, user.id));
       const days = tx.select({ id: schema.habitDays.id }).from(schema.habitDays).where(inArray(schema.habitDays.habitId, owned));
@@ -31,11 +30,12 @@ export function createAccountRoutes(db: AppDatabase, auth: ReturnType<typeof cre
     });
     c.header("Content-Disposition", 'attachment; filename="mina-habits-export.json"');
     return c.json(data);
-  });
+  }));
   app.delete("/", auth.requireSameOrigin, bodyLimit({ maxSize: 1024 }), async c => {
     const body = await c.req.json().catch(() => null);
     if (body?.confirmation !== "DELETE") return c.json({ error: "Type DELETE to confirm account deletion." }, 422);
     const userId = c.get("user").id;
+    return HabitService.withPrepared(db, c.get("user"), now, () => {
     db.transaction(tx => {
       const owned = tx.select({ id: schema.habits.id }).from(schema.habits).where(eq(schema.habits.userId, userId));
       const days = tx.select({ id: schema.habitDays.id }).from(schema.habitDays).where(inArray(schema.habitDays.habitId, owned));
@@ -50,6 +50,7 @@ export function createAccountRoutes(db: AppDatabase, auth: ReturnType<typeof cre
     });
     auth.clearSession(c);
     return c.body(null, 204);
+    });
   });
   return app;
 }

src/assets/fonts/README.md

@@ -12,3 +12,24 @@ Downloaded September 7, 2026. The files are versioned in this repository and cop
 into the production image. Browser and native canvas renderers use the alias
 `Mina Sans`; no system sans-serif font is selected for card text. The native font
 loader fails startup if a required font cannot be registered.
+
+Browser WOFF2 copies are lossless conversions of these exact TTF files using
+FontTools with Brotli; no subsetting is applied. All glyphs and Unicode mappings
+are retained (3,748 glyphs for each Noto Sans weight, 377 for each Instrument
+Serif style). Native canvas keeps using the original TTFs. CSS uses separately
+cacheable `/fonts/browser/*.woff2` URLs so font bytes do not block CSS parsing.
+
+Regenerate with `uv run --with fonttools --with brotli python`:
+
+```python
+from pathlib import Path
+from fontTools.ttLib import TTFont
+for path in Path("src/assets/fonts").glob("*.ttf"):
+    font = TTFont(path)
+    cmap, glyphs = font.getBestCmap(), font.getGlyphOrder()
+    font.flavor = "woff2"
+    font.save(path.with_suffix(".woff2"))
+    restored = TTFont(path.with_suffix(".woff2"))
+    assert restored.getBestCmap() == cmap
+    assert restored.getGlyphOrder() == glyphs
+```

src/browser-fonts.test.ts

@@ -0,0 +1,14 @@
+import { expect, test } from "bun:test";
+import { browserFont } from "./browser-fonts";
+test("browser fonts are external WOFF2 files with conditional caching and a fixed allowlist", async () => {
+  const url = "http://localhost/fonts/browser/InstrumentSerif-Regular.woff2";
+  const response = browserFont(new Request(url));
+  expect(response.status).toBe(200);
+  expect(response.headers.get("Content-Type")).toBe("font/woff2");
+  const bytes = new Uint8Array(await response.arrayBuffer());
+  expect(new TextDecoder().decode(bytes.slice(0, 4))).toBe("wOF2");
+  expect(browserFont(new Request(url, { headers: { "If-None-Match": response.headers.get("ETag")! } })).status).toBe(304);
+  expect(browserFont(new Request("http://localhost/fonts/browser/.env")).status).toBe(404);
+  expect(browserFont(new Request("http://localhost/fonts/browser/%2e%2e%2f.env")).status).toBe(404);
+  expect(await browserFont(new Request(url, { method: "HEAD" })).text()).toBe("");
+});

src/browser-fonts.ts

@@ -0,0 +1,18 @@
+import path from "node:path";
+
+const names = ["InstrumentSerif-Regular", "InstrumentSerif-Italic", "NotoSans-Regular", "NotoSans-Medium", "NotoSans-SemiBold"];
+const directory = process.env.NODE_ENV === "production" ? "fonts/browser" : "src/assets/fonts";
+const fonts: Map<string, { file: ReturnType<typeof Bun.file>; etag: string }> = new Map(names.map(name => {
+  const file = Bun.file(path.resolve(directory, `${name}.woff2`));
+  return [`${name}.woff2`, { file, etag: `"${file.size.toString(16)}-${file.lastModified.toString(16)}"` }] as const;
+}));
+
+/** Explicit allowlist: font URLs never grant access to other filesystem paths. */
+export function browserFont(request: Request): Response {
+  const name = new URL(request.url).pathname.slice("/fonts/browser/".length);
+  const font = fonts.get(name);
+  if (!font || !["GET", "HEAD"].includes(request.method)) return new Response(null, { status: 404 });
+  const headers = { "Content-Type": "font/woff2", "Cache-Control": "public, max-age=3600", ETag: font.etag };
+  if (request.headers.get("If-None-Match") === font.etag) return new Response(null, { status: 304, headers });
+  return new Response(request.method === "HEAD" ? null : font.file, { headers });
+}

src/components/ArchivedHabits.tsx

@@ -71,7 +71,7 @@ export function ArchivedHabits({ date, revision, onChanged, onExpired, onClose }
             <Button variant="text" disabled={busy || loading} aria-label={`Delete permanently ${habit.name}`} aria-haspopup="dialog" onClick={() => { setDeleteError(""); setDeleting(habit); }}><Trash2 size={16} aria-hidden="true" />Delete permanently</Button>
           </div>
         </header>
-        {selected === habit.habitId && <div className="ds-record-detail" id={`archive-history-${habit.habitId}`}><HabitHistory calendarOnly habit={habit} date={date} revision={revision + attempt} disabled={busy || loading} onExpired={onExpired} onHistorySaved={() => setAttempt(value => value + 1)} /></div>}
+        {selected === habit.habitId && <div className="ds-record-detail" id={`archive-history-${habit.habitId}`}><HabitHistory calendarOnly habit={habit} date={date} revision={habit.calendarRevision ?? revision + attempt} disabled={busy || loading} onExpired={onExpired} onHistorySaved={() => setAttempt(value => value + 1)} /></div>}
       </article>)}
     </div>
     {deleting && <Modal id="delete-archived-habit" size="compact" eyebrow="PERMANENT DELETION" title="Delete this habit?" description={`“${deleting.name ?? "Habit"}” and all its check-ins, tasks, and progress history will be permanently deleted. It will be removed from combined charts; charts with no remaining habits will also be deleted. This cannot be undone.`} busy={busy} initialFocus="[data-cancel-delete]" returnFocus={() => archiveFocus.current} onClose={() => setDeleting(null)}>

src/components/CalendarCache.test.ts

@@ -0,0 +1,27 @@
+import { afterAll, afterEach, expect, spyOn, test } from "bun:test";
+import { CalendarCache } from "./CalendarCache";
+const fetchSpy = spyOn(globalThis, "fetch");
+afterEach(() => fetchSpy.mockReset());
+afterAll(() => fetchSpy.mockRestore());
+const range = { from: "2026-07-01", to: "2026-09-30" };
+test("calendar cache shares in-flight reads, retains wider history and invalidates changed versions", async () => {
+  fetchSpy.mockImplementation(Object.assign(async () => Response.json({ from: range.from, to: range.to, days: [{ date: "2026-07-01" }, { date: "2026-09-01" }] }), { preconnect: fetch.preconnect }));
+  const cache = new CalendarCache();
+  await Promise.all([cache.load("habit", "v1", range), cache.load("habit", "v1", range)]);
+  expect(fetchSpy).toHaveBeenCalledTimes(1);
+  expect(String(fetchSpy.mock.calls[0]![0])).toContain("compact=true");
+  const subset = await cache.load("habit", "v1", { from: "2026-09-01", to: range.to });
+  expect(subset.days).toHaveLength(1);
+  expect(fetchSpy).toHaveBeenCalledTimes(1);
+  await cache.load("habit", "v2", range);
+  expect(fetchSpy).toHaveBeenCalledTimes(2);
+  await new CalendarCache().load("habit", "v2", range);
+  expect(fetchSpy).toHaveBeenCalledTimes(3);
+});
+test("a failed history request can be retried without retaining a rejected cache entry", async () => {
+  fetchSpy.mockRejectedValueOnce(new Error("offline")).mockResolvedValue(Response.json({ ...range, days: [] }));
+  const cache = new CalendarCache();
+  await expect(cache.load("habit", "v1", range)).rejects.toThrow("offline");
+  await expect(cache.load("habit", "v1", range)).resolves.toMatchObject({ days: [] });
+  expect(fetchSpy).toHaveBeenCalledTimes(2);
+});

src/components/CalendarCache.tsx

@@ -0,0 +1,34 @@
+import { createContext, useContext, useRef, type ReactNode } from "react";
+import type { CalendarResponse } from "../shared/calendar";
+import { habitRequest } from "../lib/dashboard";
+
+type Range = { from: string; to: string };
+type Entry = Range & { version: string; value: Promise<CalendarResponse> };
+/** Account-scoped, bounded cache; never survives signing out or changing accounts. */
+export class CalendarCache {
+  private entries = new Map<string, Entry[]>();
+  load(habitId: string, version: string, range: Range) {
+    const entries = (this.entries.get(habitId) ?? []).filter(entry => entry.version === version);
+    const cached = entries.find(entry => entry.from <= range.from && entry.to >= range.to);
+    if (cached) return cached.value.then(value => ({ ...value, ...range, days: value.days.filter(day => day.date >= range.from && day.date <= range.to) }));
+    const entry: Entry = { ...range, version, value: habitRequest<CalendarResponse>(`/habits/${habitId}/calendar?${new URLSearchParams({ ...range, compact: "true" })}`) };
+    entries.push(entry);
+    this.entries.delete(habitId);
+    this.entries.set(habitId, entries.slice(-8));
+    if (this.entries.size > 100) this.entries.delete(this.entries.keys().next().value!);
+    entry.value.catch(() => { const current = this.entries.get(habitId); if (current) this.entries.set(habitId, current.filter(item => item !== entry)); });
+    return entry.value;
+  }
+}
+const Context = createContext<CalendarCache | null>(null);
+export function CalendarCacheProvider({ children }: { children: ReactNode }) {
+  const cache = useRef<CalendarCache | null>(null);
+  cache.current ??= new CalendarCache();
+  return <Context.Provider value={cache.current}>{children}</Context.Provider>;
+}
+export function useCalendarCache() {
+  const shared = useContext(Context);
+  const local = useRef<CalendarCache | null>(null);
+  local.current ??= new CalendarCache();
+  return shared ?? local.current;
+}

src/components/HabitHistory.tsx

@@ -1,15 +1,17 @@
+import { useCalendarCache } from "./CalendarCache";
 import { Modal } from "./design-system/Modal";
 import { Pencil } from "lucide-react";
-import { useEffect, useRef, useState, type ReactNode } from "react";
+import { useEffect, useMemo, useRef, useState, type ReactNode } from "react";
 import type { CalendarResponse } from "../shared/calendar";
 import { habitRequest, scheduleLabel, type TodayHabit } from "../lib/dashboard";
 import { CalendarHeatmap } from "./design-system/CalendarHeatmap";
-import { monthWindow } from "./design-system/calendar-model";
+import { monthWindow, type MonthView } from "./design-system/calendar-model";
 import { Button } from "./design-system/primitives";
 import { HabitChart } from "./design-system/HabitChart";
 import { CalendarLegend } from "./design-system/CalendarLegend";
 import { shade } from "../habits/calendar";
-import { CheckInEditor } from "./CheckInEditor";
+import { deferred } from "./design-system/deferred";
+const CheckInEditor = deferred(() => import("./CheckInEditor").then(module => module.CheckInEditor));
 import { Field } from "./design-system/Field";
 import { ItemActions } from "./design-system/ItemActions";
 
@@ -40,7 +42,29 @@ export function HabitHistory({
   onHistorySaved?: () => void;
   calendarOnly?: boolean;
 }) {
+  const cache = useCalendarCache();
+  const [rangeSelection, setRangeSelection] = useState(() => ({ date, months: 3 as MonthView | "custom", range: monthWindow(date, 3) }));
+  const range = useMemo(() => {
+    if (rangeSelection.date === date || rangeSelection.months === "custom") return rangeSelection.range;
+    // A preset follows the current month across midnight; an explicitly inspected
+    // older window and custom dates retain the user's chosen historical period.
+    const previousCurrent = monthWindow(rangeSelection.date, rangeSelection.months);
+    const anchor = rangeSelection.range.to < previousCurrent.to ? rangeSelection.range.to : date;
+    return monthWindow(anchor, rangeSelection.months);
+  }, [date, rangeSelection]);
+  function requestRange(next: { from: string; to: string }, months: MonthView | "custom" = rangeSelection.months) {
+    setRangeSelection({ date, months, range: next });
+  }
+  const [historyLoading, setHistoryLoading] = useState(false);
   const [selectedDate, setSelectedDate] = useState<string>();
+  function selectDate(selected: string) {
+    setSelectedDate(selected);
+    const available = monthWindow(date, 12);
+    if (rangeSelection.months !== "custom" && selected >= available.from && selected <= available.to && (selected < range.from || selected > range.to)) {
+      const requested = monthWindow(selected, rangeSelection.months);
+      requestRange({ from: requested.from < available.from ? available.from : requested.from, to: requested.to });
+    }
+  }
   const [editingDay, setEditingDay] = useState(false);
   const [savingDay, setSavingDay] = useState(false);
   const [calendar, setCalendar] = useState<CalendarResponse | null>(null);
@@ -49,26 +73,20 @@ export function HabitHistory({
   const expired = useRef(onExpired);
   expired.current = onExpired;
   useEffect(() => {
-    const controller = new AbortController();
+    let active = true;
     setError("");
-    const range = monthWindow(date, 12);
+    setHistoryLoading(true);
-    habitRequest<CalendarResponse>(
+    cache.load(habit.habitId, `${date}:${revision}:${attempt}`, range)
-      `/habits/${habit.habitId}/calendar?${new URLSearchParams(range)}`,
+      .then(result => { if (active) setCalendar(result); })
-      { signal: controller.signal },
+      .catch(error => {
-    )
+        if (!active) return;
-      .then((result) => {
+        if (error.message.includes("session has expired") && expired.current) expired.current();
-        if (!controller.signal.aborted) setCalendar(result);
-      })
-      .catch((error) => {
-        if (controller.signal.aborted) return;
-        if (error.message.includes("session has expired") && expired.current)
-          expired.current();
         else setError(error.message);
-      });
+      }).finally(() => { if (active) setHistoryLoading(false); });
-    return () => controller.abort();
+    return () => { active = false; };
-  }, [habit.habitId, date, revision, attempt]);
+  }, [cache, habit.habitId, date, revision, attempt, range.from, range.to]);
 
-  const days =
+  const days = useMemo(() =>
     calendar?.days.map((day) => ({
       date: day.date,
       color: day.color,
@@ -80,14 +98,14 @@ export function HabitHistory({
         : day.due
           ? ("due" as const)
           : ("not-due" as const),
-    })) ?? [];
+    })) ?? [], [calendar]);
   const steps = Math.max(
     1,
     calendar?.days.find((day) => day.date === date)?.shadeCount ??
       habit.target ??
       1,
   );
-  const shades = calendar
+  const shades = useMemo(() => calendar
     ? [
         calendar.settings.emptyColor,
         ...Array.from(
@@ -101,7 +119,7 @@ export function HabitHistory({
             ).color,
         ),
       ]
-    : [];
+    : [], [calendar, steps]);
   const chart = error ? (
     <div className="ds-form-feedback">
       <p role="alert">{error}</p>
@@ -119,17 +137,20 @@ export function HabitHistory({
   ) : (
     <>
     <CalendarHeatmap
-      onSelectDate={setSelectedDate}
+      onSelectDate={selectDate}
       selectedDate={selectedDate}
       compact
       initialMonths={3}
+      availableRange={monthWindow(date, 12)}
+      onRangeChange={requestRange}
+      loading={historyLoading}
       historyLabel="Your recorded progress"
       label={`${habit.name} progress calendar`}
       unit={habit.unit}
       color={calendar.settings.mainColor}
       emptyColor={calendar.settings.emptyColor}
       days={days}
-      selectedDayAction={selected => <Button variant="secondary" disabled={disabled} aria-label="Edit selected check-in" aria-haspopup="dialog" onClick={() => { setSelectedDate(selected); setEditingDay(true); }}><Pencil size={16} aria-hidden="true" />Edit check-in</Button>}
+      selectedDayAction={selected => <Button variant="secondary" disabled={disabled} aria-label="Edit selected check-in" aria-haspopup="dialog" onClick={() => { selectDate(selected); setEditingDay(true); }}><Pencil size={16} aria-hidden="true" />Edit check-in</Button>}
       legend={
         <CalendarLegend
           label={`${habit.name} progress calendar`}
@@ -141,7 +162,7 @@ export function HabitHistory({
     />
     {editingDay && <Modal id={`check-in-${habit.habitId}`} title="Edit check-in" description={habit.name ?? "Habit"} closeLabel="Close check-in editor" onClose={() => setEditingDay(false)} busy={savingDay}>
     <div className="ds-history-editor">
-      <div className="ds-form-stack"><Field label="Check-in date">{id => <input id={id} type="date" disabled={savingDay} max={date} value={selectedDate ?? date} onChange={event => { if (event.target.value) setSelectedDate(event.target.value); }} />}</Field></div>
+      <div className="ds-form-stack"><Field label="Check-in date">{id => <input id={id} type="date" disabled={savingDay} max={date} value={selectedDate ?? date} onChange={event => { if (event.target.value) selectDate(event.target.value); }} />}</Field></div>
       <CheckInEditor key={`${habit.habitId}:${selectedDate ?? date}`} habitId={habit.habitId} date={selectedDate ?? date} disabled={disabled} onExpired={onExpired}
         onBusyChange={setSavingDay} onSaved={() => { setAttempt(value => value + 1); onHistorySaved?.(); }} />
     </div></Modal>}

src/components/design-system/CalendarHeatmap.tsx

@@ -1,6 +1,6 @@
 import { useTheme } from "../ThemeProvider";
 import { habitProgressColor, themedHabitShade } from "../../lib/habit-palette";
-import { useId, useLayoutEffect, useRef, useState, type CSSProperties, type ReactNode } from "react";
+import { useId, useMemo, useLayoutEffect, useRef, useState, type CSSProperties, type ReactNode } from "react";
 import { CalendarLegend } from "./CalendarLegend";
 import { Field } from "./Field";
 import { Button } from "./primitives";
@@ -10,6 +10,7 @@ import {
   calendarTimeline,
   MONTH_VIEWS,
   visibleCalendarDays,
+  monthWindow,
   type CalendarDay,
   type MonthView,
 } from "./calendar-model";
@@ -26,7 +27,13 @@ export function CalendarHeatmap({
   historyLabel,
   legend,
   selectedDayAction,
+  availableRange,
+  onRangeChange,
+  loading = false,
 }: {
+  availableRange?: { from: string; to: string };
+  onRangeChange?: (range: { from: string; to: string }, months: MonthView | "custom") => void;
+  loading?: boolean;
   days: CalendarDay[];
   unit: string;
   label: string;
@@ -65,15 +72,15 @@ export function CalendarHeatmap({
     if (onSelectDate) onSelectDate(date);
     else setLocalSelectedDate(date);
   }
-  const days = months === "custom" && customRange
+  const days = useMemo(() => months === "custom" && customRange
     ? allDays.filter((day) => day.date >= customRange.from && day.date <= customRange.to)
-    : anchor ? visibleCalendarDays(allDays, months === "custom" ? 12 : months, anchor) : [];
+    : anchor ? visibleCalendarDays(allDays, months === "custom" ? 12 : months, anchor) : [], [allDays, months, customRange, anchor]);
   const selected =
     days.find((day) => day.date === selectedDate) ??
     days.find((day) => day.date === anchor) ??
     days[0];
   // Date keys and the shared timeline remain stable when the chart resizes.
-  const timeline = calendarTimeline(days);
+  const timeline = useMemo(() => calendarTimeline(days), [days]);
   const buttons = useRef<(HTMLButtonElement | null)[]>([]);
   const inspectorId = useId();
   const instructionsId = useId();
@@ -100,6 +107,7 @@ export function CalendarHeatmap({
     <div
       className={`ds-calendar${compact ? " ds-calendar--compact" : ""}`}
       data-months={months}
+      aria-busy={loading}
       style={{ "--calendar-weeks": timeline.weeks, "--calendar-color": color } as CSSProperties}
     >
       <div className="ds-calendar-range-toolbar">
@@ -130,7 +138,7 @@ export function CalendarHeatmap({
               type="button"
               aria-label={`${value} ${value === 1 ? "month" : "months"}`}
               aria-pressed={months === value}
-              onClick={() => setMonths(value)}
+              onClick={() => { setMonths(value); if (anchor) onRangeChange?.(monthWindow(anchor, value), value); }}
             >
               {value}m
             </button>
@@ -142,6 +150,7 @@ export function CalendarHeatmap({
               if (!customRange) setCustomRange({ from: days[0]!.date, to: days.at(-1)!.date });
               setRangeError("");
               setMonths("custom");
+              onRangeChange?.(customRange ?? { from: days[0]!.date, to: days.at(-1)!.date }, "custom");
             }}
           >
             Custom
@@ -160,7 +169,7 @@ export function CalendarHeatmap({
             const end = form.elements.namedItem("to") as HTMLInputElement;
             const isAvailable = (input: HTMLInputElement) =>
               input.validity.valid && input.value !== "" &&
-              input.value >= allDays[0]!.date && input.value <= allDays.at(-1)!.date;
+              input.value >= (availableRange?.from ?? allDays[0]!.date) && input.value <= (availableRange?.to ?? allDays.at(-1)!.date);
             if (!isAvailable(start) || !isAvailable(end)) {
               setRangeError("Choose both dates within the available history.");
               (!isAvailable(start) ? start : end).focus();
@@ -171,11 +180,12 @@ export function CalendarHeatmap({
               end.focus();
               return;
             }
-            if (!allDays.some((day) => day.date >= start.value && day.date <= end.value)) {
+            if (!availableRange && !allDays.some((day) => day.date >= start.value && day.date <= end.value)) {
               setRangeError("There are no calendar dates in this range.");
               return;
             }
             setCustomRange({ from: start.value, to: end.value });
+            onRangeChange?.({ from: start.value, to: end.value }, "custom");
             setRangeError("");
           }}
         >
@@ -187,8 +197,8 @@ export function CalendarHeatmap({
                   name={name}
                   type="date"
                   required
-                  min={allDays[0]!.date}
+                  min={availableRange?.from ?? allDays[0]!.date}
-                  max={allDays.at(-1)!.date}
+                  max={availableRange?.to ?? allDays.at(-1)!.date}
                   defaultValue={customRange[name]}
                   aria-invalid={rangeError ? true : undefined}
                   aria-describedby={rangeError ? rangeErrorId : undefined}
@@ -201,6 +211,7 @@ export function CalendarHeatmap({
           {rangeError && <p id={rangeErrorId} className="ds-calendar-range-error" role="alert">{rangeError}</p>}
         </form>
       )}
+      {loading && <p role="status" className="ds-supporting-copy">Loading history…</p>}
       <div
         className="ds-calendar-viewport"
         role="group"

src/components/design-system/deferred.tsx

@@ -0,0 +1,9 @@
+import { lazy, Suspense, type ComponentProps, type ComponentType } from "react";
+
+/** Keep the surrounding workspace usable while an optional surface loads. */
+export function deferred<Component extends ComponentType<any>>(load: () => Promise<Component>) {
+  const Surface = lazy(async () => ({ default: await load() })) as ComponentType<ComponentProps<Component>>;
+  return function Deferred(props: ComponentProps<Component>) {
+    return <Suspense fallback={<p className="ds-supporting-copy" role="status">Loading…</p>}><Surface {...props} /></Suspense>;
+  };
+}

src/db/schema.ts

@@ -1,3 +1,4 @@
+import { sql } from 'drizzle-orm';
 import { index, integer, sqliteTable, text, uniqueIndex } from "drizzle-orm/sqlite-core";
 
 export const users = sqliteTable("users", {
@@ -33,6 +34,7 @@ export const discordDeliveries = sqliteTable("discord_deliveries", {
 // Revisions are append-only, including multiple edits on the same local date.
 export const habits = sqliteTable('habits', {
   id: text('id').primaryKey(), userId: text('user_id').notNull().references(() => users.id),
+  calendarRevision: integer('calendar_revision').notNull().default(0),
   createdDate: text('created_date').notNull(), materializedThrough: text('materialized_through'), createdAt: integer('created_at').notNull(),
 }, t => [index('habits_user_idx').on(t.userId)]);
 export const habitRevisions = sqliteTable('habit_revisions', {
@@ -47,7 +49,7 @@ export const habitDays = sqliteTable('habit_days', {
 export const taskOccurrences = sqliteTable('task_occurrences', {
   id: text('id').primaryKey(), dayId: integer('day_id').notNull().references(() => habitDays.id), taskId: text('task_id').notNull(), name: text('name').notNull(),
   done: integer('done', { mode: 'boolean' }).notNull().default(false), expiredAt: integer('expired_at'), closedAt: integer('closed_at'), updatedAt: integer('updated_at').notNull(),
-}, t => [index('task_occurrences_day_idx').on(t.dayId)]);
+}, t => [index('task_occurrences_day_idx').on(t.dayId), index('task_occurrences_open_idx').on(t.dayId).where(sql`${t.closedAt} IS NULL`)]);
 export const progressEvents = sqliteTable('progress_events', {
   id: integer('id').primaryKey({ autoIncrement: true }), dayId: integer('day_id').notNull().references(() => habitDays.id), occurrenceId: text('occurrence_id'),
   before: text('before', { mode: 'json' }).$type<unknown>().notNull(), after: text('after', { mode: 'json' }).$type<unknown>().notNull(), createdAt: integer('created_at').notNull(),

src/discord/command-graphics.ts

@@ -55,7 +55,7 @@ export function commandGraphicAction(c: Context, action: string, data: ControlDa
   ];
   const reply = message(c, content, [row(...controls)], false);
   c.defer(async () => {
-    try { return { message: reply.data as import('./types').Message, image: await renderCommandCard(model, theme), imageDescription: `${model.title}. ${model.summary}. ${model.subtitle}. Page ${model.page + 1} of ${model.pages}.` }; }
+    try { return { message: reply.data as import('./types').Message, image: await renderCommandCard(model, theme, c.service.user.id), imageDescription: `${model.title}. ${model.summary}. ${model.subtitle}. Page ${model.page + 1} of ${model.pages}.` }; }
     catch { return { message: { ...(reply.data as import('./types').Message), content: `The graphic could not be rendered.\n${content}`.slice(0, 2000) } }; }
   });
   return { type: 5, data: c.interaction.guild_id ? { flags: 64 } : {} };

src/discord/command-image.ts

@@ -1,3 +1,4 @@
+import { renderImage } from '../rendering/queue';
 import { createCanvas } from '@napi-rs/canvas';
 import '../sharing/live-card-image';
 import { themePalette, type Theme } from '../lib/theme';
@@ -7,7 +8,10 @@ export type CardRow = { label: string; detail: string; value?: string; ratio?: n
 export type CommandCard = { title: string; owner: string; subtitle: string; summary: string; note: string; rows: CardRow[]; page: number; pages: number; history?: { date: string; ratio: number | null; future: boolean; color: string }[] };
 export const commandCardSize = (data: CommandCard) => ({ width: 1200, height: 350 + Math.max(1, data.rows.length) * 116 + (data.history ? 164 : 0) + 100 });
 /** Fixed-size rows and text keep every page readable, including very large accounts. */
-export async function renderCommandCard(data: CommandCard, theme: Theme = 'light') {
+export function renderCommandCard(data: CommandCard, theme: Theme = 'light', userId = 'unscoped') {
+  return renderImage('command', userId, data, theme, () => draw(data, theme));
+}
+async function draw(data: CommandCard, theme: Theme) {
   if (data.rows.length > 6 || (data.history && data.history.length > 14)) throw new Error('Paginate command cards before rendering.');
   const { width, height } = commandCardSize(data), canvas = createCanvas(width, height), ctx = canvas.getContext('2d');
   const p = themePalette[theme];
@@ -61,5 +65,6 @@ export async function renderCommandCard(data: CommandCard, theme: Theme = 'light
   rect(64, height - 92, 1072, 1, p.rule);
   text(data.note, 64, height - 48, 21, 860, p.muted);
   text(`${data.page + 1} / ${data.pages}`, 1035, height - 48, 21, 100, p.muted);
-  return new Uint8Array(await canvas.encode('png'));
+  try { return new Uint8Array(await canvas.encode('png')); }
+  finally { canvas.width = 1; canvas.height = 1; }
 }

src/discord/progress-image.ts

@@ -1,3 +1,4 @@
+import { renderImage } from '../rendering/queue';
 import { createCanvas } from '@napi-rs/canvas';
 // Import the existing renderer's bundled font registration and data contract.
 import { type LiveImageData } from '../sharing/live-card-image';
@@ -8,7 +9,10 @@ import { cardDate } from '../lib/progress-card';
 
 export const progressImageSize = { width: 1200, height: 860 };
 /** Focused, chronological 30-day view; constant font/cell sizes at any habit count. */
-export async function renderProgressImage(data: LiveImageData, theme: Theme = 'light') {
+export function renderProgressImage(data: LiveImageData, theme: Theme = 'light', userId = 'unscoped') {
+  return renderImage('progress', userId, data, theme, () => draw(data, theme));
+}
+async function draw(data: LiveImageData, theme: Theme) {
   const habit = data.habits[0];
   if (!habit || data.habits.length !== 1 || habit.days.length !== 30) throw new Error('Choose one habit and a 30-day range.');
   const canvas = createCanvas(progressImageSize.width, progressImageSize.height);
@@ -62,5 +66,6 @@ export async function renderProgressImage(data: LiveImageData, theme: Theme = 'l
     text(item.label, x + 36, 772, 21, 230, palette.muted);
   });
   text('A little, every day.', 64, 822, 27, 1072, palette.muted, true);
-  return new Uint8Array(await canvas.encode('png'));
+  try { return new Uint8Array(await canvas.encode('png')); }
+  finally { canvas.width = 1; canvas.height = 1; }
 }

src/discord/progress.test.ts

@@ -112,3 +112,17 @@ test('snapshot quotas are shared with website operations and new controls cannot
   f.setDiscordTime('2026-09-04T12:16:00Z');
   expect((await click(preview, 'Choose public destination')).data.content).toContain('expired');
 });
+
+test('a website edit during a deferred public share invalidates the prepared snapshot', async () => {
+  const env = setup();
+  const habit = await f.json('/habits', 'POST', { name: 'Reading', method: 'manual' }, 201);
+  const panel = await f.run({ data: { name: 'progress' } });
+  await click(panel, 'Preview a habit', false, [habit.id]); const preview = await env.drain();
+  await click(preview, 'Choose public destination'); const confirmation = await env.drain();
+  await click(confirmation, 'Share snapshot publicly');
+  const delivery = env.drain();
+  await f.json(`/habits/${habit.id}/days/2026-09-04/progress`, 'PUT', { done: true });
+  const result = await delivery;
+  expect(result.data.content).toContain('changed');
+  expect(env.sends).toHaveLength(0);
+});

src/discord/progress.ts

@@ -1,6 +1,6 @@
 import { createHash } from 'node:crypto';
 import { renderProgressImage } from './progress-image';
-import { ApiError } from '../habits/service';
+import { ApiError, HabitService } from '../habits/service';
 import { liveCardData } from '../sharing/live-card-image';
 import type { createSharingRoutes } from '../sharing/routes';
 import type { createLiveDiscord } from '../sharing/live-discord';
@@ -14,9 +14,11 @@ export type ProgressOperations = {
 export type DeferredMessage = { message: Message; image?: Uint8Array; imageDescription?: string };
 const fingerprint = (value: unknown) => createHash('sha256').update(JSON.stringify(value)).digest('hex');
 function imageData(c: Context, data: ControlData) {
-  const result = liveCardData(c.db, c.service.user.id, c.now);
+  // Preparation happened before dispatch. Fresh read caches detect edits across deferred awaits.
+  const snapshot = new HabitService(c.db, c.service.user, c.now);
+  const result = liveCardData(c.db, c.service.user.id, c.now, snapshot);
   if (data.habitId) {
-    const habits = c.service.list();
+    const habits = snapshot.list();
     const index = habits.findIndex(h => h.id === data.habitId);
     if (index < 0) throw new ApiError(409, 'This habit changed. Run /progress again.');
     result.habits = [result.habits[index]!];
@@ -24,7 +26,7 @@ function imageData(c: Context, data: ControlData) {
   return { ...result, avatarUrl: null };
 }
 async function render(c: Context, data: ControlData, source = imageData(c, data)) {
-  return renderProgressImage(source, data.theme ?? 'light');
+  return renderProgressImage(source, data.theme ?? 'light', c.service.user.id);
 }
 function output(reply: Reply, image?: Uint8Array): DeferredMessage { return { message: reply.data as Message, image }; }
 function defer(c: Context, job: () => Promise<DeferredMessage>): Reply {
@@ -87,7 +89,7 @@ export function progressAction(c: Context, action: string, data: ControlData): R
         const source = imageData(c, data);
         const image = await render(c, data, source);
         if (fingerprint(imageData(c, data)) !== data.expected) throw new ApiError(409, 'Progress changed during rendering. Open a fresh preview.');
-        const delivery = await ops.sharing.send(c.service.user, data.deliveryId!, new File([image], 'mina-habits-progress.png', { type: 'image/png' }));
+        const delivery = await ops.sharing.send(c.service.user, data.deliveryId!, new File([new Uint8Array(image)], 'mina-habits-progress.png', { type: 'image/png' }));
         return output(message(c, delivery.status === 'sent' ? `Snapshot shared.${delivery.messageUrl ? ` [Open snapshot](${delivery.messageUrl})` : ''}` : 'Discord could not confirm delivery. Check the destination before creating another snapshot; this action will not be retried.', [], false));
       }
       const state = action === 'progress.pause' ? await ops.live.pause(c.service.user.id) : await ops.live.start(c.service.user, data.theme ?? 'light');

src/discord/routes.ts

@@ -54,15 +54,17 @@ export function createDiscordRoutes(db: AppDatabase, config: CommandConfig, now
     // Help needs no account creation, habit synchronization, or saved UI state.
     if (i.type === 2 && i.data?.name === 'help') return c.json(help(!!i.guild_id, config.origin));
     let pending: (() => Promise<DeferredMessage>) | undefined;
-    const reply = db.transaction((): Reply => {
+    // Resolve the account before queueing catch-up; no transaction is held across yields.
-      const existing = db.select().from(users).where(eq(users.discordId, profile.id)).get();
+    const existing = db.select().from(users).where(eq(users.discordId, profile.id)).get();
-      const userId = existing?.id ?? crypto.randomUUID();
+    const userId = existing?.id ?? crypto.randomUUID();
-      if (!existing) db.insert(users).values({ id: userId, discordId: profile.id, username: profile.username, globalName: profile.global_name, avatarHash: profile.avatar, createdAt: now(), updatedAt: now() }).run();
+    if (!existing) db.insert(users).values({ id: userId, discordId: profile.id, username: profile.username, globalName: profile.global_name, avatarHash: profile.avatar, createdAt: now(), updatedAt: now() }).run();
+    const receipt = db.select().from(discordReceipts).where(eq(discordReceipts.id, i.id)).get();
+    if (receipt && receipt.expiresAt > now()) return c.json(receipt.response);
+    const owner = publicUser(db.select().from(users).where(eq(users.id, userId)).get()!);
+    const reply = await HabitService.withPrepared(db, owner, now, service => db.transaction((): Reply => {
       const receipt = db.select().from(discordReceipts).where(eq(discordReceipts.id, i.id)).get();
       if (receipt && receipt.expiresAt > now()) return receipt.response;
-      const user = publicUser(db.select().from(users).where(eq(users.id, userId)).get()!);
       const controls = new ControlStore(db, userId, now()); controls.prune();
-      const service = new HabitService(db, user, now()); service.sync();
       const ctx: Context = { db, service, controls, interaction: i, now: now(), origin: config.origin, remindersAvailable: config.remindersAvailable ?? false, changed: () => changed(userId), progress: dispatch.progress, defer: i.token ? job => { pending = job; } : undefined };
       let result: Reply;
       try {
@@ -83,7 +85,7 @@ export function createDiscordRoutes(db: AppDatabase, config: CommandConfig, now
       }
       db.insert(discordReceipts).values({ id: i.id, userId, response: result, expiresAt: now() + 86400000 }).run();
       return result;
-    });
+    }));
     if (pending) {
       const work = pending;
       const job = async () => {

src/habits/performance.test.ts

@@ -0,0 +1,85 @@
+import { expect, test } from 'bun:test';
+import { fixture } from './test-fixture';
+import { HabitService } from './service';
+import { publicUser } from '../auth';
+import { users } from '../db/schema';
+import { eq } from 'drizzle-orm';
+
+test('single-day reads load only the selected latest snapshot and its tasks', async () => {
+  const f = fixture();
+  try {
+    const habit = await f.json('/habits', 'POST', { name: 'Tasks', method: 'tasks', tasks: [{name:'Read'}] }, 201);
+    f.setTime('2027-09-04T12:00:00Z');
+    await f.json('/today');
+    const logs: string[] = [];
+    (f.db as any).session.logger = { logQuery(query: string) { logs.push(query); } };
+    const service = new HabitService(f.db, publicUser(f.db.select().from(users).where(eq(users.id,'alice')).get()!), Date.parse('2027-09-04T12:00:00Z'));
+    const day = service.day(habit.id, '2027-09-04');
+    expect(day.tasks).toHaveLength(1);
+    expect((service as any).recordsCache.get(habit.id).size).toBe(1);
+    expect((service as any).occurrencesCache.get(habit.id).size).toBe(1);
+    expect(logs.find(query => query.includes('task_occurrences'))).toContain('"habit_days"."date" >=');
+  } finally { f.close(); }
+});
+
+test('calendar summaries omit editor payloads and mutation versions cover historical changes', async () => {
+  const f = fixture();
+  try {
+    const habit = await f.json('/habits', 'POST', { name: 'Tasks', method: 'tasks', tasks: [{name:'Read'}] }, 201);
+    const first = (await f.json('/today')).habits[0];
+    expect((await f.json('/today')).habits[0].calendarRevision).toBe(first.calendarRevision);
+    f.setTime('2026-09-05T12:00:00Z');
+    await f.json(`/habits/${habit.id}/days/2026-09-04/tasks/${first.tasks[0].taskId}`, 'PUT', {done:true});
+    const changed = (await f.json('/today')).habits[0].calendarRevision;
+    expect(changed).toBeGreaterThan(first.calendarRevision);
+    await f.json(`/habits/${habit.id}/calendar-settings`, 'PUT', {mainColor:'#123456'});
+    expect((await f.json('/today')).habits[0].calendarRevision).toBeGreaterThan(changed);
+    const url = `/habits/${habit.id}/calendar?from=2026-09-04&to=2026-09-05`;
+    const full = await f.json(url);
+    const compact = await f.json(url+'&compact=true');
+    const detail = full.days[0].habits[0];
+    const {tasks, requirements, ...summary} = detail;
+    expect(compact.days[0].habits[0]).toEqual(summary);
+    expect(compact.data).toEqual(full.data);
+    expect((await f.json(`/habits/${habit.id}/days/2026-09-04`)).tasks[0].done).toBe(true);
+  } finally { f.close(); }
+});
+
+test('unchanged dashboard and calendar reads write no rows after synchronization', async () => {
+  const f = fixture();
+  try {
+    const habit = await f.json('/habits', 'POST', {name:'Tasks', method:'tasks', tasks:[{name:'Read'}]}, 201);
+    f.setTime('2027-09-04T12:00:00Z');
+    await f.json('/today');
+    const before = (f.sqlite.query('SELECT total_changes() AS n').get() as {n:number}).n;
+    await f.json('/today');
+    await f.json(`/habits/${habit.id}/calendar?from=2027-09-01&to=2027-09-04&compact=true`);
+    expect((f.sqlite.query('SELECT total_changes() AS n').get() as {n:number}).n).toBe(before);
+  } finally {f.close();}
+});
+
+test('catch-up yields to other users and serializes same-user edits until fully ready', async () => {
+  const f = fixture();
+  try {
+    const habit = await f.json('/habits', 'POST', {name:'Many tasks', method:'tasks', tasks:Array.from({length:50}, (_,i)=>({name:`Task ${i}`}))}, 201);
+    f.setTime('2027-09-04T12:00:00Z');
+    let complete = false;
+    const dashboard = f.json('/today').then(value => {complete=true; return value;});
+    await new Promise(resolve=>setTimeout(resolve,0));
+    expect(complete).toBe(false);
+    // Another user's request can complete while Alice is still catching up.
+    expect((await f.request('/today','GET',undefined,'b')).status).toBe(200);
+    expect(complete).toBe(false);
+    // The actual date can advance while catch-up yields; readiness revalidates it.
+    f.setTime('2027-09-05T12:00:00Z');
+    const edit = f.json(`/habits/${habit.id}`, 'PATCH', {name:'Renamed'});
+    const [today, changed] = await Promise.all([dashboard, edit]);
+    expect(today.date).toBe('2027-09-05');
+    expect(today.habits[0].tasks).toHaveLength(50);
+    expect(changed.name).toBe('Renamed');
+    const through = f.sqlite.query('SELECT materialized_through AS date FROM habits WHERE id=?').get(habit.id) as {date:string};
+    expect(through.date).toBe('2027-09-05');
+    const day = await f.json(`/habits/${habit.id}/days/2026-09-05`);
+    expect(day.tasks.every((task:any)=>task.expiredAt!==null && task.closedAt!==null)).toBe(true);
+  } finally {f.close();}
+});

src/habits/routes.ts

@@ -20,7 +20,7 @@ function date(c: Context<Env>) {
   return result.data;
 }
 function range(c: Context<Env>) {
-  const result = z.object({ from: dateSchema, to: dateSchema }).strict().safeParse(c.req.query());
+  const result = z.object({ from: dateSchema, to: dateSchema, compact: z.enum(['true', 'false']).optional() }).strict().safeParse(c.req.query());
   if (!result.success || result.data.from > result.data.to || dayNumber(result.data.to) - dayNumber(result.data.from) > 1829) throw new ApiError(422, 'Supply from and to dates in order, spanning at most 1830 days');
   return result.data;
 }
@@ -41,8 +41,9 @@ export function createHabitRoutes(db: AppDatabase, auth: ReturnType<typeof creat
           try { payload.value = await c.req.json(); } catch { payload.malformed = true; }
         }
         c.set('payload', payload);
-        const service = new HabitService(db, c.get('user'), now());
+        await HabitService.withPrepared(db, c.get('user'), now, async service => {
-        service.sync(); c.set('service', service); await next();
+          c.set('service', service); await next();
+        });
       }); if (response) c.res = response; };
       if (!['GET', 'HEAD', 'OPTIONS'].includes(c.req.method)) {
         const response = await origin(c, proceed); if (response) c.res = response;
@@ -80,7 +81,7 @@ export function createHabitRoutes(db: AppDatabase, auth: ReturnType<typeof creat
   app.get('/habits/:id/calendar-settings', c => c.json(service(c).settings(id(c))));
   app.put('/habits/:id/calendar-settings', c => c.json(service(c).saveSettings(id(c), body(c, calendarSettingsSchema))));
   app.get('/habits/:id/calendar', c => {
-    const { from, to } = range(c); return c.json(service(c).calendar([id(c)], from, to, service(c).settings(id(c)), false));
+    const { from, to, compact } = range(c); return c.json(service(c).calendar([id(c)], from, to, service(c).settings(id(c)), false, compact === 'true'));
   });
   app.get('/today', c => {
     const s = service(c); const habits = s.list().map(h => s.day(h.id, s.today));
@@ -100,7 +101,7 @@ export function createHabitRoutes(db: AppDatabase, auth: ReturnType<typeof creat
   });
   app.delete('/charts/:id', c => { service(c).deleteChart(id(c)); return c.body(null, 204); });
   app.get('/charts/:id/calendar', c => {
-    const chart = service(c).chart(id(c)); const { from, to } = range(c); return c.json(service(c).calendar(chart.habitIds, from, to, chart.settings, true));
+    const chart = service(c).chart(id(c)); const { from, to, compact } = range(c); return c.json(service(c).calendar(chart.habitIds, from, to, chart.settings, true, compact === 'true'));
   });
   app.get('/charts/:id/days/:date', c => {
     const chart = service(c).chart(id(c)); const day = date(c); return c.json(service(c).calendar(chart.habitIds, day, day, chart.settings, true).days[0]);

src/habits/service.ts

@@ -1,4 +1,4 @@
-import { and, asc, desc, eq, inArray, lte, sql } from 'drizzle-orm';
+import { and, asc, desc, eq, inArray, lte, gte, gt, lt, or, isNull, sql } from 'drizzle-orm';
 import type { AppDatabase } from '../auth';
 import type { PublicUser } from '../shared/user';
 import { habits, habitRevisions, habitDays, taskOccurrences, progressEvents, habitCalendarSettings, combinedCharts, users } from '../db/schema';
@@ -13,17 +13,59 @@ export type Habit = typeof habits.$inferSelect;
 export type Revision = typeof habitRevisions.$inferSelect;
 export type HabitDay = typeof habitDays.$inferSelect;
 
+// Each database has its own per-user readiness queue. No transaction spans a yield.
+const preparationQueues = new WeakMap<AppDatabase, Map<string, Promise<void>>>();
 export class HabitService {
+  static async withPrepared<T>(db: AppDatabase, user: PublicUser, now: () => number, run: (service: HabitService) => T | Promise<T>): Promise<T> {
+    let queues = preparationQueues.get(db);
+    if (!queues) { queues = new Map(); preparationQueues.set(db, queues); }
+    const previous = queues.get(user.id);
+    let release!: () => void;
+    const ticket = new Promise<void>(resolve => { release = resolve; });
+    queues.set(user.id, ticket);
+    if (previous) await previous;
+    try {
+      let sliceStarted = performance.now();
+      while (true) {
+        // Re-read timezone, date and owned records after every scheduling yield.
+        const service = new HabitService(db, user, now());
+        const habit = service.pending()[0];
+        if (!habit) {
+          service.sync();
+          return await run(service);
+        }
+        const start = habit.materializedThrough ? addDays(habit.materializedThrough, 1) : habit.createdDate;
+        const through = [addDays(start, 7), service.today].sort()[0]!;
+        db.transaction(() => service.materialize(habit, through));
+        if (performance.now() - sliceStarted >= 8) {
+          await new Promise<void>(resolve => setTimeout(resolve, 0));
+          sliceStarted = performance.now();
+        }
+      }
+    } finally {
+      release();
+      if (queues.get(user.id) === ticket) queues.delete(user.id);
+    }
+  }
+  /** Ready read snapshot. Use withPrepared for read-modify-write handlers. */
+  static prepare(db: AppDatabase, user: PublicUser, now: () => number) {
+    return HabitService.withPrepared(db, user, now, service => service);
+  }
+
   readonly today: string;
   private ownedCache = new Map<string, Habit>();
   private revisionCache = new Map<string, Revision[]>();
   private deadlineCache = new Map<string, number>();
+  private ranges = new Map<string, { from: string; to: string }>();
+  private revisionRanges = new Map<string, { from: string; to: string }>();
   private recordsCache = new Map<string, Map<string, HabitDay>>();
   private occurrencesCache = new Map<string, Map<number, (typeof taskOccurrences.$inferSelect)[]>>();
   private countCache = new Map<string, Map<string, { value: number; carriedFrom: string | null }>>();
   constructor(readonly db: AppDatabase, readonly user: PublicUser, readonly now: number) {
     // A different request may update the timezone while this request's body streams in.
-    const timezone = db.select({ timezone: users.timezone }).from(users).where(eq(users.id, user.id)).get()!.timezone;
+    const currentUser = db.select({ timezone: users.timezone }).from(users).where(eq(users.id, user.id)).get();
+    if (!currentUser) throw missing();
+    const timezone = currentUser.timezone;
     this.user = { ...user, timezone };
     // Travel west must never reopen or rewrite earlier requirements.
     const latest = db.select({ date: habits.materializedThrough }).from(habits).where(eq(habits.userId, user.id)).orderBy(desc(habits.materializedThrough)).get()?.date;
@@ -35,10 +77,27 @@ export class HabitService {
     if (!habit) throw missing();
     this.ownedCache.set(id, habit); return habit;
   }
+  private loadRevisions(id: string, from: string, to: string) {
+    const first = this.db.select().from(habitRevisions).where(and(eq(habitRevisions.habitId, id), lte(habitRevisions.effectiveDate, from))).orderBy(desc(habitRevisions.effectiveDate), desc(habitRevisions.id)).get();
+    const later = from === to ? [] : this.db.select().from(habitRevisions).where(and(eq(habitRevisions.habitId, id), gt(habitRevisions.effectiveDate, from), lte(habitRevisions.effectiveDate, to))).orderBy(desc(habitRevisions.effectiveDate), desc(habitRevisions.id)).all();
+    this.revisionCache.set(id, first ? [...later, first] : later);
+    this.revisionRanges.set(id, { from, to });
+  }
   revision(id: string, date = this.today): Revision | undefined {
-    let revisions = this.revisionCache.get(id);
+    const range = this.revisionRanges.get(id);
-    if (!revisions) { revisions = this.db.select().from(habitRevisions).where(eq(habitRevisions.habitId, id)).orderBy(desc(habitRevisions.effectiveDate), desc(habitRevisions.id)).all(); this.revisionCache.set(id, revisions); }
+    if (!range || date < range.from || date > range.to) this.loadRevisions(id, date, date);
-    return revisions.find(r => r.effectiveDate <= date);
+    return this.revisionCache.get(id)!.find(r => r.effectiveDate <= date);
+  }
+  private range(id: string, from: string, to = from) {
+    const old = this.ranges.get(id);
+    if (old && from >= old.from && to <= old.to) return;
+    this.ranges.set(id, { from, to });
+    this.recordsCache.delete(id); this.occurrencesCache.delete(id); this.countCache.delete(id);
+    this.loadRevisions(id, from, to);
+  }
+  private changed(id: string) {
+    this.db.update(habits).set({ calendarRevision: sql`${habits.calendarRevision} + 1` }).where(eq(habits.id, id)).run();
+    this.ownedCache.delete(id);
   }
   current(id: string) {
     const habit = this.owned(id); const revision = this.revision(id)!;
@@ -47,11 +106,11 @@ export class HabitService {
       ? [{ code: 'no_tasks', taskId: null, message: 'Add a task to make this habit due.' }]
       : config.tasks.filter(task => !schedulesOverlap(config.schedule, task.schedule))
         .map(task => ({ code: 'task_never_due', taskId: task.id, message: `Task \"${task.name}\" never coincides with the habit schedule.` }));
-    return { id: habit.id, ...config, warnings, createdDate: habit.createdDate, createdAt: habit.createdAt, revisionId: revision.id, effectiveDate: revision.effectiveDate };
+    return { id: habit.id, calendarRevision: habit.calendarRevision, ...config, warnings, createdDate: habit.createdDate, createdAt: habit.createdAt, revisionId: revision.id, effectiveDate: revision.effectiveDate };
   }
   list(includeArchived = false) {
     return this.db.select().from(habits).where(eq(habits.userId, this.user.id)).orderBy(asc(habits.createdAt), asc(habits.id)).all()
-      .map(h => this.current(h.id)).filter(h => includeArchived || !h.archived);
+      .map(h => { this.ownedCache.set(h.id, h); return this.current(h.id); }).filter(h => includeArchived || !h.archived);
   }
   create(input: ReturnType<typeof habitInput.parse>) {
     const id = crypto.randomUUID();
@@ -114,7 +173,8 @@ export class HabitService {
     this.owned(id);
     this.db.transaction(() => {
       this.db.insert(habitRevisions).values({ habitId: id, effectiveDate: this.today, config, createdAt: this.now }).run();
-      this.materialize(this.owned(id));
+      this.materialize(this.owned(id), this.today, true);
+      this.changed(id);
     });
     return this.current(id);
   }
@@ -137,19 +197,25 @@ export class HabitService {
   }
   sync() {
     this.db.transaction(() => {
-      for (const habit of this.db.select().from(habits).where(eq(habits.userId, this.user.id)).all()) this.materialize(habit);
+      for (const habit of this.pending()) this.materialize(habit);
-      // Record the original deadline even after downtime. Only active day snapshots expire.
+      // Start with the small partial index of open occurrences rather than
+      // revisiting every historical snapshot on every unchanged request.
       this.db.run(sql`UPDATE task_occurrences SET
         expired_at = CASE WHEN done = 0 THEN COALESCE(expired_at, (SELECT ends_at FROM habit_days WHERE id = task_occurrences.day_id)) ELSE expired_at END,
         closed_at = (SELECT ends_at FROM habit_days WHERE id = task_occurrences.day_id)
-        WHERE closed_at IS NULL AND day_id IN (
+        WHERE id IN (
-          SELECT d.id FROM habit_days d JOIN habits h ON h.id = d.habit_id
+          SELECT o.id FROM task_occurrences o INDEXED BY task_occurrences_open_idx
-          WHERE h.user_id = ${this.user.id} AND d.ends_at <= ${this.now}
+          CROSS JOIN habit_days d ON d.id = o.day_id
+          CROSS JOIN habits h ON h.id = d.habit_id
+          WHERE o.closed_at IS NULL AND h.user_id = ${this.user.id} AND d.ends_at <= ${this.now}
           AND d.id = (SELECT MAX(d2.id) FROM habit_days d2 WHERE d2.habit_id = d.habit_id AND d2.date = d.date))`);
     });
   }
+  private pending() {
+    return this.db.select().from(habits).where(and(eq(habits.userId, this.user.id), or(isNull(habits.materializedThrough), lt(habits.materializedThrough, this.today)))).all();
+  }
   private invalidate(id: string) {
-    this.countCache.delete(id); this.revisionCache.delete(id); this.recordsCache.delete(id); this.occurrencesCache.delete(id); this.ownedCache.delete(id);
+    this.ranges.delete(id); this.revisionRanges.delete(id); this.countCache.delete(id); this.revisionCache.delete(id); this.recordsCache.delete(id); this.occurrencesCache.delete(id); this.ownedCache.delete(id);
   }
   private deadline(date: string) {
     let value = this.deadlineCache.get(date);
@@ -160,7 +226,7 @@ export class HabitService {
     let records = this.recordsCache.get(id);
     if (!records) {
       records = new Map();
-      for (const day of this.db.select().from(habitDays).where(eq(habitDays.habitId, id)).orderBy(asc(habitDays.id)).all()) records.set(day.date, day);
+      for (const day of this.db.select().from(habitDays).where(and(eq(habitDays.habitId, id), gte(habitDays.date, this.ranges.get(id)!.from), lte(habitDays.date, this.ranges.get(id)!.to), sql`${habitDays.id} = (SELECT MAX(d.id) FROM habit_days d WHERE d.habit_id = ${habitDays.habitId} AND d.date = ${habitDays.date})`)).all()) records.set(day.date, day);
       this.recordsCache.set(id, records);
     }
     return records;
@@ -169,15 +235,17 @@ export class HabitService {
     let occurrences = this.occurrencesCache.get(id);
     if (!occurrences) {
       occurrences = new Map();
-      const rows = this.db.select({ occurrence: taskOccurrences }).from(taskOccurrences).innerJoin(habitDays, eq(taskOccurrences.dayId, habitDays.id)).where(eq(habitDays.habitId, id)).orderBy(asc(taskOccurrences.id)).all();
+      const rows = this.db.select({ occurrence: taskOccurrences }).from(taskOccurrences).innerJoin(habitDays, eq(taskOccurrences.dayId, habitDays.id)).where(and(eq(habitDays.habitId, id), gte(habitDays.date, this.ranges.get(id)!.from), lte(habitDays.date, this.ranges.get(id)!.to), sql`${habitDays.id} = (SELECT MAX(d.id) FROM habit_days d WHERE d.habit_id = ${habitDays.habitId} AND d.date = ${habitDays.date})`)).orderBy(asc(taskOccurrences.id)).all();
       for (const { occurrence } of rows) { const entries = occurrences.get(occurrence.dayId) ?? []; entries.push(occurrence); occurrences.set(occurrence.dayId, entries); }
       this.occurrencesCache.set(id, occurrences);
     }
     return occurrences;
   }
-  private materialize(habit: Habit) {
+  private materialize(habit: Habit, through = this.today, force = false) {
-    let date = habit.materializedThrough ?? habit.createdDate;
+    let date = force ? through : habit.materializedThrough ? addDays(habit.materializedThrough, 1) : habit.createdDate;
-    while (date <= this.today) {
+    if (date > through) return;
+    this.loadRevisions(habit.id, date, through);
+    while (date <= through) {
       const revision = this.revision(habit.id, date)!;
       const existing = this.db.select().from(habitDays).where(and(eq(habitDays.habitId, habit.id), eq(habitDays.date, date))).orderBy(desc(habitDays.id)).get();
       if (!existing || existing.revisionId !== revision.id) {
@@ -193,23 +261,43 @@ export class HabitService {
             .innerJoin(habitDays, eq(taskOccurrences.dayId, habitDays.id))
             .where(and(eq(habitDays.habitId, habit.id), eq(habitDays.date, date)))
             .orderBy(desc(habitDays.id)).all().map(row => row.occurrence) : [];
-          for (const task of revision.config.tasks.filter(t => scheduled(t.schedule, date))) {
+          const occurrences = revision.config.tasks.filter(t => scheduled(t.schedule, date)).map(task => {
             const old = previous.find(t => t.taskId === task.id);
-            this.db.insert(taskOccurrences).values({ id: crypto.randomUUID(), dayId: day.id, taskId: task.id, name: task.name,
+            return { id: crypto.randomUUID(), dayId: day.id, taskId: task.id, name: task.name,
-              done: old?.done ?? false, expiredAt: old ? old.expiredAt : day.endsAt <= this.now ? day.endsAt : null, closedAt: old?.closedAt ?? (day.endsAt <= this.now ? day.endsAt : null), updatedAt: old?.updatedAt ?? this.now }).run();
+              done: old?.done ?? false, expiredAt: old ? old.expiredAt : day.endsAt <= this.now ? day.endsAt : null, closedAt: old?.closedAt ?? (day.endsAt <= this.now ? day.endsAt : null), updatedAt: old?.updatedAt ?? this.now };
-          }
+          });
+          if (occurrences.length) this.db.insert(taskOccurrences).values(occurrences).run();
         }
       }
       date = addDays(date, 1);
     }
-    this.db.update(habits).set({ materializedThrough: this.today }).where(eq(habits.id, habit.id)).run();
+    this.db.update(habits).set({ materializedThrough: through }).where(eq(habits.id, habit.id)).run();
   }
   private counts(id: string) {
     const cached = this.countCache.get(id); if (cached) return cached;
-    const rows = this.db.select({ day: habitDays, config: habitRevisions.config }).from(habitDays)
+    const range = this.ranges.get(id)!;
-      .innerJoin(habitRevisions, eq(habitDays.revisionId, habitRevisions.id))
+    const latest = sql`${habitDays.id} = (SELECT MAX(d.id) FROM habit_days d WHERE d.habit_id = ${habitDays.habitId} AND d.date = ${habitDays.date})`;
-      .where(and(eq(habitDays.habitId, id), sql`${habitDays.id} = (SELECT MAX(d.id) FROM habit_days d WHERE d.habit_id = ${habitDays.habitId} AND d.date = ${habitDays.date})`))
+    const select = () => this.db.select({ day: habitDays, config: habitRevisions.config }).from(habitDays).innerJoin(habitRevisions, eq(habitDays.revisionId, habitRevisions.id));
-      .orderBy(asc(habitDays.date)).all();
+    const rows = select().where(and(eq(habitDays.habitId, id), gte(habitDays.date, range.from), lte(habitDays.date, range.to), latest)).orderBy(asc(habitDays.date)).all();
+    // Only carry-enabled ranges need a prefix. Walk backwards in bounded pages
+    // until a logged value or requirements reset establishes the starting state.
+    const first = rows.find(({day, config}) => config.method !== 'count' || config.archived || scheduled(config.schedule, day.date));
+    if (first?.config.method === 'count' && first.config.carryPartialProgress && !first.day.countSet) {
+      let before = range.from;
+      const prefix: typeof rows = [];
+      let found = false;
+      while (!found) {
+        const page = select().where(and(eq(habitDays.habitId, id), lt(habitDays.date, before), latest)).orderBy(desc(habitDays.date)).limit(64).all();
+        if (!page.length) break;
+        for (const entry of page) {
+          prefix.push(entry);
+          const { day, config } = entry;
+          if (config.method !== 'count' || config.archived || (scheduled(config.schedule, day.date) && (day.countSet || !config.carryPartialProgress))) { found = true; break; }
+        }
+        before = page.at(-1)!.day.date;
+      }
+      rows.unshift(...prefix.reverse());
+    }
     const result = new Map<string, { value: number; carriedFrom: string | null }>();
     let carry = 0; let source: string | null = null;
     for (const { day, config } of rows) {
@@ -223,6 +311,7 @@ export class HabitService {
   }
   day(id: string, date: string) {
     this.owned(id);
+    this.range(id, date);
     const revision = this.revision(id, date);
     const record = this.records(id).get(date);
     const config = revision?.config;
@@ -235,7 +324,7 @@ export class HabitService {
     const value = !due ? 0 : config!.method === 'count' ? counted?.value ?? 0 : config!.method === 'manual' ? Number(record?.done ?? false) : tasks.filter(t => t.done).length;
     const target = !config ? null : config.method === 'count' ? config.target : config.method === 'manual' ? 1 : tasks.length;
     const ratio = due ? Math.min(1, value / target!) : null;
-    return { date, habitId: id, name: config?.name ?? null, method: config?.method ?? null, revisionId: revision?.id ?? null,
+    return { date, habitId: id, calendarRevision: this.owned(id).calendarRevision, name: config?.name ?? null, method: config?.method ?? null, revisionId: revision?.id ?? null,
       timezone: record?.timezone ?? this.user.timezone, endsAt: record?.endsAt ?? null, due, future,
       status: future ? 'future' : !due ? 'not_due' : ratio === 1 ? 'complete' : value > 0 ? 'partial' : 'empty',
       value, target, carriedFrom: counted?.carriedFrom ?? null, loggedCount: record?.countSet ? record.count : null, unit: config?.method === 'count' ? config.unit : config?.method === 'tasks' ? 'tasks' : 'completion',
@@ -256,6 +345,7 @@ export class HabitService {
     this.db.transaction(() => {
       this.db.insert(progressEvents).values({ dayId: record.id, before: { count: detail.value, done: record.done, loggedCount: record.countSet ? record.count : null, carriedFrom: detail.carriedFrom }, after: input, createdAt: this.now }).run();
       this.db.update(habitDays).set('count' in input ? { ...input, countSet: true } : input).where(eq(habitDays.id, record.id)).run();
+      this.changed(id);
     });
     this.invalidate(id);
     return this.day(id, date);
@@ -267,6 +357,7 @@ export class HabitService {
     this.db.transaction(() => {
       this.db.insert(progressEvents).values({ dayId: record.id, occurrenceId: occurrence.id, before: { done: occurrence.done }, after: { done }, createdAt: this.now }).run();
       this.db.update(taskOccurrences).set({ done, updatedAt: this.now }).where(eq(taskOccurrences.id, occurrence.id)).run();
+      this.changed(id);
     });
     this.invalidate(id);
     return this.day(id, date);
@@ -290,6 +381,7 @@ export class HabitService {
   saveSettings(id: string, settings: CalendarSettings) {
     this.owned(id);
     this.db.insert(habitCalendarSettings).values({ habitId: id, settings }).onConflictDoUpdate({ target: habitCalendarSettings.habitId, set: { settings } }).run();
+    this.changed(id);
     return settings;
   }
   chart(id: string) {
@@ -306,8 +398,8 @@ export class HabitService {
     return this.chart(id);
   }
   deleteChart(id: string) { this.chart(id); this.db.delete(combinedCharts).where(eq(combinedCharts.id, id)).run(); }
-  calendar(ids: string[], from: string, to: string, settings: CalendarSettings, combined: boolean) {
+  calendar(ids: string[], from: string, to: string, settings: CalendarSettings, combined: boolean, compact = false) {
-    ids.forEach(id => this.owned(id));
+    ids.forEach(id => { this.owned(id); this.range(id, from, to); });
     const days = [];
     for (let date = from; date <= to; date = addDays(date, 1)) {
       const details = ids.map(id => this.day(id, date));
@@ -318,7 +410,10 @@ export class HabitService {
       const progress = shade(ratio, steps, settings, !combined && (settings.shadeCount === 'auto' || manual));
       const future = date > this.today;
       days.push({ date, due: due.length, completed, ratio, future, status: future ? 'future' : ratio === null ? 'not_due' : ratio === 1 ? 'complete' : ratio > 0 ? 'partial' : 'empty',
-        shadeCount: steps, ...progress, color: future ? settings.futureColor : progress.color, habits: details });
+        shadeCount: steps, ...progress, color: future ? settings.futureColor : progress.color, habits: details.map(detail => {
+          const { tasks, requirements, ...summary } = detail;
+          return { ...summary, tasks: compact ? undefined : tasks, requirements: compact ? undefined : requirements };
+        }) });
     }
     return { kind: combined ? 'combined' as const : 'individual' as const, from, to, today: this.today, timezone: this.user.timezone, settings, days,
       // Explicit colors and details are supplied for the client's Nivo colorScale/tooltip adapters.

src/index.ts

@@ -1,3 +1,4 @@
+import { browserFont } from "./browser-fonts";
 import { startReminders } from "./reminders/worker";
 import { backupConfig, startBackups } from "./ops/backups";
 import { databasePath } from "./db/config";
@@ -15,6 +16,7 @@ if (process.env.NODE_ENV !== "production") {
 }
 
 const backups = process.env.NODE_ENV === "production" ? startBackups(sqlite, backupConfig(databasePath)) : undefined;
+await backups?.ready;
 if (import.meta.hot) import.meta.hot.dispose(() => backups?.stop());
 
 const reminders = process.env.NODE_ENV === "production" ? startReminders(db, { token: readDiscordSharingConfig().token, origin: readAuthConfig().origin, commandsAvailable: /^[a-f\d]{64}$/i.test(process.env.DISCORD_PUBLIC_KEY ?? "") && Boolean(readAuthConfig().clientId) }) : undefined;
@@ -28,6 +30,7 @@ const server = Bun.serve({
   hostname: process.env.HOST ?? "127.0.0.1",
   port: Number(process.env.PORT ?? 3000),
   routes: {
+    "/fonts/browser/*": browserFont,
     "/api": req => app.fetch(req),
     "/api/*": req => app.fetch(req),
     "/*": index,

src/lib/dashboard.ts

@@ -46,3 +46,15 @@ export function formatTrackingDate(date: string) {
     timeZone: "UTC",
   });
 }
+
+/** Preserve unchanged row references when a background refresh returns new JSON objects. */
+export function reconcileToday(current: TodayResponse | null, next: TodayResponse): TodayResponse {
+  if (!current || current.date !== next.date || current.timezone !== next.timezone) return next;
+  const previous = new Map(current.habits.map(habit => [habit.habitId, habit]));
+  const habits = next.habits.map(habit => {
+    const old = previous.get(habit.habitId);
+    return old && JSON.stringify(old) === JSON.stringify(habit) ? old : habit;
+  });
+  if (current.due === next.due && current.completed === next.completed && habits.length === current.habits.length && habits.every((habit, index) => habit === current.habits[index])) return current;
+  return { ...next, habits };
+}

src/ops/backups.test.ts

@@ -1,6 +1,6 @@
 import { expect, test } from "bun:test";
 import { Database } from "bun:sqlite";
-import { mkdtempSync, mkdirSync, readdirSync, rmSync, statSync, writeFileSync } from "node:fs";
+import { existsSync, mkdtempSync, mkdirSync, readdirSync, rmSync, statSync, writeFileSync } from "node:fs";
 import { join } from "node:path";
 import { tmpdir } from "node:os";
 import { fixture } from "../habits/test-fixture";
@@ -35,6 +35,7 @@ test("WAL snapshots restore committed progress, revoke sessions, replicate, and
     expect(readdirSync(config.replica!)).toHaveLength(2);
     expect(readdirSync(config.directory)).toContain("keep.txt");
     const runner = startBackups(f.sqlite, config);
+    await runner.ready;
     expect(runner.state.failed).toBe(false); expect(runner.state.lastSuccess).toBeGreaterThan(0); runner.stop();
   } finally { f.close(); rmSync(directory, { recursive: true, force: true }); }
 });
@@ -71,3 +72,78 @@ test("backup and restore CLIs work against a live database without overwriting i
     expect(f.sqlite.query('SELECT count(*) AS n FROM sessions').get()).toEqual({ n: 2 });
   } finally { f.close(); rmSync(directory, { recursive: true, force: true }); }
 });
+
+test('scheduled backups yield to the event loop, retain WAL data, and verify replicas', async () => {
+  const directory = mkdtempSync(join(tmpdir(), 'minabot-async-backup-'));
+  const path = join(directory, 'live.sqlite'), f = fixture(path);
+  let runner: ReturnType<typeof startBackups> | undefined;
+  try {
+    f.sqlite.exec('PRAGMA journal_mode=WAL');
+    await f.json('/habits', 'POST', { name: 'Async snapshot', method: 'manual' }, 201);
+    const config = backupConfig(path, { BACKUP_REPLICA_DIR: 'replica' });
+    mkdirSync(config.replica!);
+    let yielded = false;
+    const timer = new Promise<void>(resolve => setTimeout(() => { yielded = true; resolve(); }, 0));
+    runner = startBackups(path, config);
+    expect(runner.state.lastSuccess).toBe(0);
+    await runner.ready;
+    expect(yielded).toBe(true); await timer;
+    expect(runner.state.failed).toBe(false);
+    expect(runner.state.lastSuccess).toBeGreaterThan(0);
+    const snapshots = readdirSync(config.directory).filter(file => file.endsWith('.sqlite'));
+    expect(snapshots).toHaveLength(1);
+    const check = new Database(join(config.replica!, snapshots[0]!), { readonly: true });
+    try { expect(check.query('SELECT count(*) AS n FROM habits').get()).toEqual({ n: 1 }); } finally { check.close(); }
+    await runner.tick();
+    expect(readdirSync(config.directory).filter(file => file.endsWith('.sqlite'))).toHaveLength(1);
+  } finally { runner?.stop(); f.close(); rmSync(directory, { recursive: true, force: true }); }
+});
+
+test('scheduled backup ticks coalesce, expose failure and recovery, and stop admitting work', async () => {
+  const config = backupConfig('/tmp/test-only.sqlite', {});
+  let calls = 0, release!: (value: number) => void;
+  const run = async () => { calls++; return new Promise<number>(resolve => { release = resolve; }); };
+  const runner = startBackups('/tmp/test-only.sqlite', config, run);
+  expect(runner.tick()).toBe(runner.ready);
+  expect(calls).toBe(1);
+  release(123); await runner.ready;
+  expect(runner.state.lastSuccess).toBe(123);
+  const second = runner.tick(); expect(calls).toBe(2);
+  runner.stop(); release(456); await second;
+  await runner.tick(); expect(calls).toBe(2);
+  const failed = startBackups('/tmp/test-only.sqlite', config, async () => { throw new Error('test failure'); });
+  await failed.ready; expect(failed.state.failed).toBe(true); failed.stop();
+  const disabled = startBackups('/tmp/test-only.sqlite', { ...config, enabled: false }, run);
+  await disabled.ready; expect(calls).toBe(2); disabled.stop();
+});
+
+
+test('the first scheduled snapshot initializes cold WAL bookkeeping without changing source rows', async () => {
+  const directory = mkdtempSync(join(tmpdir(), 'minabot-cold-wal-'));
+  const path = join(directory, 'live.sqlite'), f = fixture(path);
+  f.sqlite.exec('PRAGMA journal_mode=DELETE'); f.close();
+  const db = new Database(path, { readwrite: true, create: false, strict: true });
+  let runner: ReturnType<typeof startBackups> | undefined;
+  try {
+    db.exec('PRAGMA journal_mode=WAL');
+    expect(existsSync(`${path}-shm`)).toBe(false);
+    runner = startBackups(db, backupConfig(path, {}));
+    await runner.ready;
+    expect(runner.state.failed).toBe(false);
+    expect(runner.state.lastSuccess).toBeGreaterThan(0);
+    expect(db.query('SELECT count(*) AS n FROM users').get()).toEqual({ n: 2 });
+    expect(db.query('SELECT count(*) AS n FROM sessions').get()).toEqual({ n: 2 });
+    expect(db.query('SELECT total_changes() AS n').get()).toEqual({ n: 0 });
+  } finally { runner?.stop(); db.close(); rmSync(directory, { recursive: true, force: true }); }
+});
+
+test('the scheduled snapshot never creates a missing source database', async () => {
+  const directory = mkdtempSync(join(tmpdir(), 'minabot-missing-source-'));
+  const path = join(directory, 'missing.sqlite');
+  const runner = startBackups(path, backupConfig(path, {}));
+  try {
+    await runner.ready;
+    expect(runner.state.failed).toBe(true);
+    expect(existsSync(path)).toBe(false);
+  } finally { runner.stop(); rmSync(directory, { recursive: true, force: true }); }
+});

src/ops/backups.ts

@@ -1,3 +1,4 @@
+import { fileURLToPath } from "node:url";
 import { Database } from "bun:sqlite";
 import { chmodSync, closeSync, constants, copyFileSync, existsSync, fsyncSync, linkSync, mkdirSync, openSync, readdirSync, renameSync, rmSync, statSync, unlinkSync } from "node:fs";
 import { dirname, join, resolve } from "node:path";
@@ -82,18 +83,40 @@ export function restoreBackup(source: string, destination: string) {
   } finally { if (existsSync(temporary)) unlinkSync(temporary); }
   return destination;
 }
-export function startBackups(database: Database, config: BackupConfig) {
+/** Runs all filesystem and SQLite backup work in a separate Bun process. */
-  const state = { enabled: config.enabled, lastSuccess: 0, failed: false };
+export async function runScheduledBackup(database: string, config: BackupConfig): Promise<number> {
-  if (!config.enabled) return { state, stop() {} };
+  const source = new URL("../../scripts/scheduled-backup.ts", import.meta.url);
-  const tick = () => {
+  const built = new URL("../scripts/scheduled-backup.ts", import.meta.url);
-    try {
+  const script = fileURLToPath(existsSync(source) ? source : built);
-      const latest = latestBackupTime(config);
+  const child = Bun.spawn([process.execPath, script, resolve(database), JSON.stringify(config)], {
-      if (latest && Date.now() - latest < config.intervalMs) { state.lastSuccess = latest; state.failed = false; return; }
+    stdout: "pipe", stderr: "ignore",
-      createBackup(database, config); state.lastSuccess = Date.now(); state.failed = false;
+  });
-      console.log(JSON.stringify({ event: "backup_completed", timestamp: new Date().toISOString() }));
+  const [output, status] = await Promise.all([new Response(child.stdout).text(), child.exited]);
-    } catch { state.failed = true; console.error(JSON.stringify({ event: "backup_failed", timestamp: new Date().toISOString() })); }
+  if (status !== 0) throw new Error("Scheduled backup process failed");
-  };
+  const { timestamp, created } = JSON.parse(output) as { timestamp: number; created: boolean };
-  tick();
+  if (!Number.isFinite(timestamp) || timestamp <= 0) throw new Error("Scheduled backup returned an invalid timestamp");
-  const timer = setInterval(tick, 60000); timer.unref();
+  if (created) console.log(JSON.stringify({ event: "backup_completed", timestamp: new Date(timestamp).toISOString() }));
-  return { state, stop: () => clearInterval(timer) };
+  return timestamp;
+}
+export function startBackups(database: Database | string, config: BackupConfig, run = runScheduledBackup) {
+  const state = { enabled: config.enabled, lastSuccess: 0, failed: false };
+  let running: Promise<void> | undefined;
+  let stopped = false;
+  const tick = (): Promise<void> => {
+    if (stopped || !config.enabled) return Promise.resolve();
+    if (running) return running;
+    running = (async () => {
+      try {
+        const path = typeof database === 'string' ? database : database.filename;
+        if (!path || path === ':memory:') throw new Error('Scheduled backups require a file database');
+        state.lastSuccess = await run(path, config); state.failed = false;
+      } catch { state.failed = true; console.error(JSON.stringify({ event: "backup_failed", timestamp: new Date().toISOString() })); }
+    })().finally(() => { running = undefined; });
+    return running;
+  };
+  // Callers await readiness before accepting traffic, matching the original startup check.
+  const ready = tick();
+  const timer = config.enabled ? setInterval(() => { void tick(); }, 60000) : undefined;
+  timer?.unref();
+  return { state, ready, tick, stop: () => { stopped = true; clearInterval(timer); } };
 }

src/pages/Home.tsx

@@ -1,7 +1,9 @@
+import { deferred } from "../components/design-system/deferred";
+import { CalendarCacheProvider } from "../components/CalendarCache";
 import { Archive, Plus, Settings2 } from "lucide-react";
-import { ArchivedHabits } from "../components/ArchivedHabits";
+const ArchivedHabits = deferred(() => import("../components/ArchivedHabits").then(module => module.ArchivedHabits));
-import { AccountSettings } from "../components/AccountSettings";
+const AccountSettings = deferred(() => import("../components/AccountSettings").then(module => module.AccountSettings));
-import { useCallback, useEffect, useRef, useState } from "react";
+import { memo, useCallback, useEffect, useRef, useState } from "react";
 import { useAuth } from "../components/AuthProvider";
 import { DiscordSignInButton } from "../components/DiscordSignInButton";
 import { PageLayout } from "../components/design-system/PageLayout";
@@ -15,17 +17,17 @@ import {
 import { Card, CardGrid } from "../components/design-system/Card";
 import { HabitChart } from "../components/design-system/HabitChart";
 import { HABIT_COLORS } from "../components/design-system/calendar-model";
-import { HabitForm } from "../components/HabitForm";
+const HabitForm = deferred(() => import("../components/HabitForm").then(module => module.HabitForm));
-import { habitRequest, scheduleLabel, type TodayHabit, type TodayResponse } from "../lib/dashboard";
+import { habitRequest, reconcileToday, scheduleLabel, type TodayHabit, type TodayResponse } from "../lib/dashboard";
 import { HabitHistory } from "../components/HabitHistory";
 import { WelcomePanel } from "../components/design-system/WelcomePanel";
 import type { PublicUser } from "../shared/user";
 import { ItemActions } from "../components/design-system/ItemActions";
 import { type ItemMode } from "../components/InlineItemForm";
-import { InlineHabitEditor } from "../components/InlineHabitEditor";
+const InlineHabitEditor = deferred(() => import("../components/InlineHabitEditor").then(module => module.InlineHabitEditor));
-import { InlineTaskEditor } from "../components/InlineTaskEditor";
+const InlineTaskEditor = deferred(() => import("../components/InlineTaskEditor").then(module => module.InlineTaskEditor));
 import type { Schedule } from "../habits/contracts";
-import { ShareProgress } from "../components/ShareProgress";
+const ShareProgress = deferred(() => import("../components/ShareProgress").then(module => module.ShareProgress));
 
 export function Home() {
   const { user, loading, busy, error, accountError, signIn, signOut, retry } = useAuth();
@@ -63,7 +65,7 @@ export function Home() {
           </Card>
         </section>
       ) : user ? (
-        <Dashboard key={user.id} user={user} onExpired={retry} />
+        <CalendarCacheProvider key={`${user.id}:${user.timezone}`}><Dashboard user={user} onExpired={retry} /></CalendarCacheProvider>
       ) : (
         <Welcome onSignIn={signIn} />
       )}
@@ -161,9 +163,10 @@ function Welcome({ onSignIn }: { onSignIn: () => void }) {
 
 function Dashboard({ user, onExpired }: { user: PublicUser; onExpired: () => void }) {
   const [today, setToday] = useState<TodayResponse | null>(null);
+  const todaySnapshot = useRef(today);
+  todaySnapshot.current = today;
   const [error, setError] = useState("");
   const [revision, setRevision] = useState(0);
-  const [calendarRevision, setCalendarRevision] = useState(0);
   const [habitRevisions, setHabitRevisions] = useState<Record<string, number>>({});
   const [pendingHabits, setPendingHabits] = useState<Set<string>>(new Set());
   const progressSaves = useRef(new Set<string>());
@@ -203,10 +206,10 @@ function Dashboard({ user, onExpired }: { user: PublicUser; onExpired: () => voi
     habitRequest<TodayResponse>("/today", { signal: controller.signal })
       .then((data) => {
         if (!controller.signal.aborted) {
-          setToday(data);
+          const next = reconcileToday(todaySnapshot.current, data);
+          setToday(next);
           setNeedsRefresh(false);
-          setRevision((value) => value + 1);
+          if (next !== todaySnapshot.current) setRevision((value) => value + 1);
-          setCalendarRevision((value) => value + 1);
         }
       })
       .catch((error) => {
@@ -302,7 +305,7 @@ function Dashboard({ user, onExpired }: { user: PublicUser; onExpired: () => voi
       try {
         const refreshed = await habitRequest<TodayResponse>("/today");
         if (mounted.current) {
-          setToday(refreshed);
+          setToday(current => reconcileToday(current, refreshed));
           // Keep a habit reachable when an edit makes it unscheduled (including an empty routine).
           if (refreshed.habits.some(item => item.habitId === habit.habitId && !item.due)) setHabitView("all");
           setNeedsRefresh(false);
@@ -337,6 +340,13 @@ function Dashboard({ user, onExpired }: { user: PublicUser; onExpired: () => voi
     }
   }
 
+  const actions = useRef({ update, manage });
+  actions.current = { update, manage };
+  const updateHabit = useCallback((...args: Parameters<typeof update>) => actions.current.update(...args), []);
+  const manageHabit = useCallback((...args: Parameters<typeof manage>) => actions.current.manage(...args), []);
+  const refreshHistory = useCallback(() => setAttempt(value => value + 1), []);
+  const expire = useCallback(() => expired.current(), []);
+
   return (
     <>
       <WelcomePanel
@@ -457,12 +467,12 @@ function Dashboard({ user, onExpired }: { user: PublicUser; onExpired: () => voi
                     key={habit.habitId}
                     habit={habit}
                     date={today.date}
-                    revision={calendarRevision + (habitRevisions[habit.habitId] ?? 0)}
+                    revision={habit.calendarRevision ?? habitRevisions[habit.habitId] ?? 0}
                     disabled={busy || pendingHabits.has(habit.habitId) || loading || needsRefresh}
-                    onHistorySaved={() => setAttempt(value => value + 1)}
+                    onHistorySaved={refreshHistory}
-                    onUpdate={update}
+                    onUpdate={updateHabit}
-                    onManage={manage}
+                    onManage={manageHabit}
-                    onExpired={() => expired.current()}
+                    onExpired={expire}
                   />
                 ))}
               </div>
@@ -474,7 +484,7 @@ function Dashboard({ user, onExpired }: { user: PublicUser; onExpired: () => voi
   );
 }
 
-function SavedHabit({
+const SavedHabit = memo(function SavedHabit({
   habit,
   date,
   revision,
@@ -604,7 +614,7 @@ function SavedHabit({
       ) : undefined}
     </HabitHistory>
   );
-}
+});
 
 function SavedTask({
   task,

src/reminders/worker.test.ts

@@ -1,4 +1,4 @@
-import { expect, test } from "bun:test";
+import { expect, test, spyOn } from "bun:test";
 import { eq } from "drizzle-orm";
 import { fixture } from "../habits/test-fixture";
 import { reminderDeliveries, reminderSettings } from "../db/schema";
@@ -213,3 +213,55 @@ test("messages include names only for the applicable reminders in the delivery b
     expect(JSON.parse(sent[1]!).allowed_mentions.parse).toEqual([]);
   } finally { f.close(); }
 });
+
+
+test('delivered slots skip habit evaluation while later slots and retries remain eligible', async () => {
+  const { f } = await setup(); const sent: string[] = [];
+  const { HabitService } = await import('../habits/service');
+  let sync: ReturnType<typeof spyOn> | undefined;
+  try {
+    f.db.update(reminderSettings).set({ quietStart: '00:00', quietEnd: '00:00', reminders: [
+      { type: 'date', date: '2026-09-04', time: '10:00' }, { type: 'date', date: '2026-09-04', time: '12:00' },
+    ] }).run();
+    const tick = (clock: string) => sendDueReminders(f.db, config, transport(sent), () => Date.parse(`2026-09-04T${clock}:00Z`));
+    await tick('08:00'); expect(sent).toHaveLength(1);
+    sync = spyOn(HabitService.prototype, 'sync');
+    for (let i = 0; i < 5; i++) await tick('08:30');
+    expect(sync).not.toHaveBeenCalled(); expect(sent).toHaveLength(1);
+    await tick('10:00'); expect(sync).toHaveBeenCalled(); expect(sent).toHaveLength(2);
+  } finally { sync?.mockRestore(); f.close(); }
+});
+
+test('reminder catch-up yields and rechecks opt-out before claiming or sending', async () => {
+  const f = fixture(); let requests = 0;
+  try {
+    await f.json('/habits', 'POST', { name: 'Backlog', method: 'tasks', tasks: Array.from({ length: 50 }, (_, i) => ({ name: `Task ${i}` })) }, 201);
+    f.db.insert(reminderSettings).values({ userId: 'alice', ...defaultReminder, enabled: true, updatedAt: 0 }).run();
+    const work = sendDueReminders(f.db, config, async () => { requests++; throw new Error('No sends expected'); }, () => Date.parse('2027-09-04T18:00:00Z'));
+    await new Promise(resolve => setTimeout(resolve, 0));
+    f.db.update(reminderSettings).set({ enabled: false }).run();
+    await work;
+    expect(requests).toBe(0);
+    expect(f.db.select().from(reminderDeliveries).all()).toHaveLength(0);
+  } finally { f.close(); }
+});
+
+test('an opt-out queued at readiness completion prevents the final reminder POST', async () => {
+  const { f } = await setup(); let posts = 0, evaluations = 0;
+  const { HabitService } = await import('../habits/service');
+  const original = HabitService.withPrepared;
+  const prepare = spyOn(HabitService, 'withPrepared').mockImplementation((db, user, now, run) => original(db, user, now, service => {
+    const result = run(service);
+    if (++evaluations === 2) queueMicrotask(() => f.db.update(reminderSettings).set({ enabled: false }).run());
+    return result;
+  }));
+  try {
+    await sendDueReminders(f.db, config, async url => {
+      if (!url.endsWith('/users/@me/channels')) posts++;
+      return Response.json({ id: '223456789012345678' });
+    }, () => Date.parse('2026-09-04T18:00:00Z'));
+    expect(evaluations).toBe(2);
+    expect(posts).toBe(0);
+    expect(f.db.select().from(reminderDeliveries).get()?.status).toBe('skipped');
+  } finally { prepare.mockRestore(); f.close(); }
+});

src/reminders/worker.ts

@@ -22,22 +22,42 @@ export async function sendDueReminders(db: AppDatabase, config: ReminderConfig,
   // Retain recent delivery history and deduplication records without unbounded growth.
   db.delete(reminderDeliveries).where(lt(reminderDeliveries.updatedAt, now() - 90 * 86400000)).run();
   for (const { user } of rows) {
-    function due() {
+    function eligible(checkDeliveries = false) {
       const currentUser = db.select().from(users).where(eq(users.id, user.id)).get();
       const prefs = db.select().from(reminderSettings).where(eq(reminderSettings.userId, user.id)).get();
       if (!currentUser || !prefs?.enabled) return null;
       const timestamp = now(); const clock = localClock(timestamp, currentUser.timezone);
       if (inQuietHours(clock, prefs.quietStart, prefs.quietEnd)) return null;
-      const times = timesForDate(prefs, localDate(timestamp, currentUser.timezone)).filter(time => time <= clock);
+      const date = localDate(timestamp, currentUser.timezone);
+      const times = timesForDate(prefs, date).filter(time => time <= clock);
       if (!times.length) return null;
-      const service = new HabitService(db, { id: currentUser.id, discordId: currentUser.discordId, username: currentUser.username, displayName: currentUser.globalName ?? currentUser.username, avatarUrl: null, timezone: currentUser.timezone }, timestamp);
+      if (checkDeliveries) {
-      service.sync();
+        const previous = db.select().from(reminderDeliveries).where(and(eq(reminderDeliveries.userId, user.id), eq(reminderDeliveries.date, date))).all();
-      // Avoid sending an artificial "today" after a backwards timezone change.
+        // This is only a cheap eligibility hint. The transaction below still owns claims.
-      if (service.today !== localDate(timestamp, currentUser.timezone)) return null;
+        // Let stale pending records reach its recovery step before skipping the user.
-      const remaining = service.list().filter(habit => { const day = service.day(habit.id, service.today); return day.due && !day.complete; }).length;
+        const stalePending = previous.some(row => row.status === 'pending' && row.updatedAt < timestamp - 60000);
-      return remaining ? { date: service.today, remaining, timezone: currentUser.timezone, times, entries: entriesForDate(prefs, service.today) } : null;
+        if (!stalePending) {
+          const legacy = previous.find(row => row.slot === '*');
+          const claimable = (prior: typeof previous[number] | undefined) => !prior || (prior.status === 'deferred' && (prior.retryAt ?? 0) <= timestamp);
+          if (previous.some(row => row.status === 'pending') || (legacy ? !claimable(legacy) : !times.some(slot => claimable(previous.find(row => row.slot === slot))))) return null;
+        }
+      }
+      return { currentUser, prefs, date, times };
     }
-    const initial = due(); if (!initial) continue;
+    function readDue(prepared?: HabitService, checkDeliveries = false) {
+      const latest = eligible(checkDeliveries); if (!latest) return null;
+      const owner = latest.currentUser;
+      const service = prepared ?? new HabitService(db, { id: owner.id, discordId: owner.discordId, username: owner.username, displayName: owner.globalName ?? owner.username, avatarUrl: null, timezone: owner.timezone }, now());
+      if (service.today !== latest.date || service.user.timezone !== owner.timezone) return null;
+      const remaining = service.list().filter(habit => { const day = service.day(habit.id, service.today); return day.due && !day.complete; }).length;
+      return remaining ? { date: service.today, remaining, timezone: service.user.timezone, times: latest.times, entries: entriesForDate(latest.prefs, service.today) } : null;
+    }
+    async function due(checkDeliveries = false) {
+      const initial = eligible(checkDeliveries); if (!initial) return null;
+      const owner = initial.currentUser;
+      return HabitService.withPrepared(db, { id: owner.id, discordId: owner.discordId, username: owner.username, displayName: owner.globalName ?? owner.username, avatarUrl: null, timezone: owner.timezone }, now, service => readDue(service, checkDeliveries));
+    }
+    const initial = await due(true); if (!initial) continue;
     const claims = db.transaction(tx => {
       // A crashed/aborted send must not block later times indefinitely.
       tx.update(reminderDeliveries).set({ status: "uncertain" }).where(and(eq(reminderDeliveries.userId, user.id), eq(reminderDeliveries.status, "pending"), lt(reminderDeliveries.updatedAt, now() - 60000))).run();
@@ -75,7 +95,10 @@ export async function sendDueReminders(db: AppDatabase, config: ReminderConfig,
     const destination = channel.ok ? await channel.json().catch(() => null) as { id?: string } | null : null;
     if (!destination?.id || !/^\d{17,20}$/.test(destination.id)) { update("failed"); continue; }
     // A user may opt out or finish a habit while Discord opens the DM channel.
-    const latest = due();
+    const prepared = await due();
+    // Releasing readiness can run a queued edit before this continuation. Re-read
+    // synchronously, with fresh caches, and invoke POST without another yield.
+    const latest = prepared ? readDue() : null;
     if (!latest || latest.date !== initial.date || !claims.some(claim => claim.slot === "*" || latest.times.includes(claim.slot))) { update("skipped"); continue; }
     const names = [...new Set(latest.entries.filter(entry => claims.some(claim => claim.slot === "*" ? latest.times.includes(entry.time) : claim.slot === entry.time)).map(entry => entry.name?.trim()).filter((name): name is string => Boolean(name)))];
     // Bound the label prefix so the count and link always fit Discord's message limit.

src/rendering/queue.test.ts

@@ -0,0 +1,27 @@
+import { expect, test } from 'bun:test';
+import { createRenderQueue, RenderBusyError } from './queue';
+
+const result = new Uint8Array([1, 2, 3]);
+test('render queue bounds global concurrency and shares only the same owner and content', async () => {
+  const queue = createRenderQueue({ concurrency: 2, maxPending: 4, maxPerUser: 2 });
+  let active = 0, peak = 0, calls = 0;
+  const run = async () => { calls++; active++; peak = Math.max(peak, active); await Bun.sleep(5); active--; return result; };
+  const first = queue('alice', 'one', run);
+  expect(queue('alice', 'one', run)).toBe(first);
+  const all = [first, queue('alice', 'two', run), queue('bob', 'one', run), queue('carol', 'one', run)];
+  await Promise.all(all); expect(calls).toBe(4); expect(peak).toBe(2);
+  expect(await queue('alice', 'one', run)).toBe(result); expect(calls).toBe(5);
+});
+
+test('render admission enforces per-user and global capacity and recovers after failures', async () => {
+  const queue = createRenderQueue({ concurrency: 1, maxPending: 2, maxPerUser: 1 });
+  let release!: () => void;
+  const first = queue('alice', 'a', async () => { await new Promise<void>(resolve => { release = resolve; }); throw new Error('render failed'); });
+  const failure = first.catch(error => error);
+  await expect(queue('alice', 'b', async () => result)).rejects.toBeInstanceOf(RenderBusyError);
+  const second = queue('bob', 'b', async () => result);
+  await expect(queue('carol', 'c', async () => result)).rejects.toBeInstanceOf(RenderBusyError);
+  while (!release) await Bun.sleep(1);
+  release(); expect((await failure).message).toBe('render failed'); await second;
+  expect(await queue('alice', 'a', async () => result)).toBe(result);
+});

src/rendering/queue.ts

@@ -0,0 +1,42 @@
+import { createHash } from 'node:crypto';
+import { ApiError } from '../habits/service';
+
+export class RenderBusyError extends ApiError {
+  constructor() { super(429, 'Image rendering is busy. Try again shortly.'); }
+}
+type Job = { run: () => Promise<Uint8Array>; resolve: (image: Uint8Array) => void; reject: (reason: unknown) => void };
+/** One process-wide admission boundary for every server canvas renderer. */
+export function createRenderQueue({ concurrency = 2, maxPending = 16, maxPerUser = 2 } = {}) {
+  const pending = new Map<string, Promise<Uint8Array>>();
+  const owners = new Map<string, number>();
+  const waiting: Job[] = [];
+  let active = 0;
+  function pump() {
+    while (active < concurrency && waiting.length) {
+      const job = waiting.shift()!; active++;
+      // Yield before drawing so a burst of callers cannot monopolize this turn.
+      setTimeout(() => {
+        void Promise.resolve().then(job.run).then(job.resolve, job.reject).finally(() => { active--; pump(); });
+      }, 0);
+    }
+  }
+  return (userId: string, key: string, run: Job['run']): Promise<Uint8Array> => {
+    const scopedKey = JSON.stringify([userId, key]);
+    const existing = pending.get(scopedKey);
+    if (existing) return existing;
+    if (pending.size >= maxPending || (owners.get(userId) ?? 0) >= maxPerUser) return Promise.reject(new RenderBusyError());
+    owners.set(userId, (owners.get(userId) ?? 0) + 1);
+    const work = new Promise<Uint8Array>((resolve, reject) => { waiting.push({ run, resolve, reject }); }).finally(() => {
+      pending.delete(scopedKey);
+      const count = owners.get(userId)! - 1;
+      if (count) owners.set(userId, count); else owners.delete(userId);
+    });
+    pending.set(scopedKey, work); pump();
+    return work;
+  };
+}
+const schedule = createRenderQueue();
+export function renderImage(kind: string, userId: string, data: unknown, theme: string, run: Job['run']) {
+  const hash = createHash('sha256').update(JSON.stringify([kind, data, theme])).digest('hex');
+  return schedule(userId, hash, run);
+}

src/sharing/avatar-cache.test.ts

@@ -0,0 +1,38 @@
+import { expect, test } from 'bun:test';
+import { createCanvas } from '@napi-rs/canvas';
+import { createAvatarCache } from './avatar-cache';
+
+test('avatars share in-flight downloads and invalidate by URL or expiry', async () => {
+  const png = await createCanvas(16, 16).encode('png');
+  let calls = 0, timestamp = 0;
+  const request = Object.assign(async () => { calls++; return new Response(new Uint8Array(png)); }, { preconnect: fetch.preconnect });
+  const avatar = createAvatarCache({ request, now: () => timestamp, successTtlMs: 100 });
+  const [one, two] = await Promise.all([avatar('avatar/hash1'), avatar('avatar/hash1')]);
+  expect(one).not.toBeNull(); expect(one).toBe(two); expect(calls).toBe(1);
+  expect(await avatar('avatar/hash1')).toBe(one); expect(calls).toBe(1);
+  await avatar('avatar/hash2'); expect(calls).toBe(2);
+  timestamp = 100; await avatar('avatar/hash1'); expect(calls).toBe(3);
+});
+
+test('avatar cache evicts least recently used images and retries negative entries after their TTL', async () => {
+  const png = await createCanvas(16, 16).encode('png');
+  let calls = 0, timestamp = 0, fail = false;
+  const request = Object.assign(async () => { calls++; return fail ? new Response(null, { status: 503 }) : new Response(new Uint8Array(png)); }, { preconnect: fetch.preconnect });
+  const avatar = createAvatarCache({ request, now: () => timestamp, maxEntries: 2, failureTtlMs: 10 });
+  await avatar('a'); await avatar('b'); await avatar('a'); await avatar('c');
+  expect(calls).toBe(3); await avatar('b'); expect(calls).toBe(4);
+  fail = true;
+  expect(await avatar('bad')).toBeNull(); expect(await avatar('bad')).toBeNull(); expect(calls).toBe(5);
+  timestamp = 10; fail = false;
+  expect(await avatar('bad')).not.toBeNull(); expect(calls).toBe(6);
+});
+
+test('avatar downloads have a concurrency bound and oversized decoded images use the fallback', async () => {
+  let release!: (response: Response) => void, calls = 0;
+  const request = Object.assign(async () => { calls++; return new Promise<Response>(resolve => { release = resolve; }); }, { preconnect: fetch.preconnect });
+  const avatar = createAvatarCache({ request, maxPending: 1 });
+  const first = avatar('one'), duplicate = avatar('one');
+  expect(await avatar('two')).toBeNull(); expect(calls).toBe(1);
+  release(new Response(new Uint8Array(await createCanvas(257, 1).encode('png'))));
+  expect(await first).toBeNull(); expect(await duplicate).toBeNull();
+});

src/sharing/avatar-cache.ts

@@ -0,0 +1,61 @@
+import { loadImage } from '@napi-rs/canvas';
+
+async function boundedBytes(response: Response) {
+  const reader = response.body?.getReader();
+  if (!reader) return null;
+  const chunks: Uint8Array[] = []; let size = 0;
+  try {
+    while (true) {
+      const { value, done } = await reader.read();
+      if (done) return Buffer.concat(chunks);
+      size += value.byteLength;
+      if (size > 1024 * 1024) { await reader.cancel(); return null; }
+      chunks.push(value);
+    }
+  } finally { reader.releaseLock(); }
+}
+
+type Avatar = Awaited<ReturnType<typeof loadImage>>;
+type Options = {
+  request?: typeof fetch;
+  now?: () => number;
+  maxEntries?: number;
+  maxPending?: number;
+  successTtlMs?: number;
+  failureTtlMs?: number;
+};
+/** Hash-based Discord URLs invalidate naturally; bound both cached images and downloads. */
+export function createAvatarCache({ request = ((url, init) => fetch(url, init)) as typeof fetch, now = Date.now, maxEntries = 128, maxPending = 4, successTtlMs = 3600000, failureTtlMs = 30000 }: Options = {}) {
+  const cache = new Map<string, { image: Avatar | null; expires: number }>();
+  const pending = new Map<string, Promise<Avatar | null>>();
+  return async (url: string): Promise<Avatar | null> => {
+    const cached = cache.get(url);
+    if (cached && cached.expires > now()) {
+      cache.delete(url); cache.set(url, cached);
+      return cached.image;
+    }
+    cache.delete(url);
+    const existing = pending.get(url);
+    if (existing) return existing;
+    if (pending.size >= maxPending) return null;
+    const job = (async () => {
+      let image: Avatar | null = null;
+      try {
+        const response = await request(url, { redirect: 'error', signal: AbortSignal.timeout(3000) });
+        if (response.ok) {
+          const bytes = await boundedBytes(response);
+          if (bytes) {
+            const decoded = await loadImage(Buffer.from(bytes));
+            if (decoded.width <= 256 && decoded.height <= 256) image = decoded;
+          }
+        }
+      } catch { /* A brief negative cache keeps an unavailable CDN out of the hot path. */ }
+      cache.set(url, { image, expires: now() + (image ? successTtlMs : failureTtlMs) });
+      while (cache.size > maxEntries) cache.delete(cache.keys().next().value!);
+      return image;
+    })().finally(() => { pending.delete(url); });
+    pending.set(url, job);
+    return job;
+  };
+}
+export const cachedAvatar = createAvatarCache();

src/sharing/live-card-image.ts

@@ -1,7 +1,9 @@
-import { createCanvas, GlobalFonts, loadImage } from "@napi-rs/canvas";
+import { renderImage } from '../rendering/queue';
+import { cachedAvatar } from './avatar-cache';
+import { createCanvas, GlobalFonts } from "@napi-rs/canvas";
 import { existsSync } from "node:fs";
 import { eq } from "drizzle-orm";
-import type { AppDatabase } from "../auth";
+import { publicUser, type AppDatabase } from "../auth";
 import { users } from "../db/schema";
 import { HabitService, ApiError } from "../habits/service";
 import { addDays } from "../habits/calendar";
@@ -23,11 +25,16 @@ for (const [file, family] of [
   }
 }
 
-export function liveCardData(db: AppDatabase, userId: string, now: number) {
+export async function loadLiveCardData(db: AppDatabase, userId: string, now: () => number) {
+  const user = db.select().from(users).where(eq(users.id, userId)).get();
+  if (!user) throw new ApiError(404, 'Account unavailable.');
+  return HabitService.withPrepared(db, publicUser(user), now, service => liveCardData(db, userId, service.now, service));
+}
+export function liveCardData(db: AppDatabase, userId: string, now: number, prepared?: HabitService) {
   const user = db.select().from(users).where(eq(users.id, userId)).get();
   if (!user) throw new ApiError(404, "Account unavailable.");
-  const service = new HabitService(db, { ...user, displayName: user.globalName ?? user.username, avatarUrl: null }, now);
+  const service = prepared ?? new HabitService(db, { ...user, displayName: user.globalName ?? user.username, avatarUrl: null }, now);
-  service.sync();
+  if (!prepared) service.sync();
   const from = addDays(service.today, -29);
   const avatarUrl = /^\d{17,20}$/.test(user.discordId) && /^(?:a_)?[a-f0-9]{32}$/i.test(user.avatarHash ?? '')
     ? `https://cdn.discordapp.com/avatars/${user.discordId}/${user.avatarHash}.png?size=128` : null;
@@ -47,18 +54,15 @@ export function liveCardLayout(count: number) {
 }
 
 /** A deterministic 16:9 PNG. Every active habit receives a panel; none are paginated away. */
-export async function renderLiveCard(data: LiveImageData, theme: Theme) {
+export function renderLiveCard(data: LiveImageData, theme: Theme, userId = 'unscoped') {
+  return renderImage('live', userId, data, theme, () => draw(data, theme));
+}
+async function draw(data: LiveImageData, theme: Theme) {
   const layout = liveCardLayout(data.habits.length);
   const canvas = createCanvas(layout.width, layout.height);
   const ctx = canvas.getContext('2d');
   const colors = themePalette[theme];
-  let avatar: Awaited<ReturnType<typeof loadImage>> | null = null;
+  const avatar = data.avatarUrl ? await cachedAvatar(data.avatarUrl) : null;
-  if (data.avatarUrl) {
-    try {
-      const response = await fetch(data.avatarUrl, { redirect: 'error', signal: AbortSignal.timeout(3000) });
-      if (response.ok) avatar = await loadImage(Buffer.from(await response.arrayBuffer()));
-    } catch { /* Match the snapshot card's neutral avatar fallback. */ }
-  }
   const rect = (x: number, y: number, w: number, h: number, color: string, radius = 0) => {
     ctx.fillStyle = color; ctx.beginPath(); ctx.roundRect(x, y, Math.max(0, w), Math.max(0, h), radius); ctx.fill();
   };
@@ -132,5 +136,6 @@ export async function renderLiveCard(data: LiveImageData, theme: Theme) {
   rect(64, 1010, 1792, 1, colors.rule);
   text('Totals cover this entire period', 64, 1050, 28, 1200, colors.muted);
   ctx.textAlign = 'right'; text(`${data.habits.length} active habits`, 1856, 1050, 28, 536, colors.muted);
-  return canvas.encode('png');
+  try { return new Uint8Array(await canvas.encode('png')); }
+  finally { canvas.width = 1; canvas.height = 1; }
 }

src/sharing/live-discord.ts

@@ -1,3 +1,4 @@
+import { RenderBusyError } from '../rendering/queue';
 import { createHash, randomBytes } from "node:crypto";
 import { eq } from "drizzle-orm";
 import { Hono } from "hono";
@@ -7,7 +8,7 @@ import type { AppDatabase, AuthEnv, createAuth } from "../auth";
 import { liveDiscordCards, users } from "../db/schema";
 import { ApiError } from "../habits/service";
 import { endOfDay, localDate } from "../habits/calendar";
-import { liveCardData, renderLiveCard } from "./live-card-image";
+import { loadLiveCardData, renderLiveCard } from "./live-card-image";
 import type { PublicUser } from "../shared/user";
 import type { DiscordSharingConfig } from "./config";
 import type { DiscordFetch } from "./routes";
@@ -64,7 +65,7 @@ export function createLiveDiscord(db: AppDatabase, auth: ReturnType<typeof creat
     const delay = Math.max(current.retryAt ?? 0, channelRetryAt) - now();
     if (delay > 0) { schedule(id, delay); return; }
     update(id, { dirty: false, retryAt: null });
-    const data = liveCardData(db, id, now());
+    const data = await loadLiveCardData(db, id, now);
     // Hash the rendered content, excluding timestamps and private task details.
     const hash = createHash('sha256').update(JSON.stringify({ data, theme: current.theme, renderer: 3, content: liveMessageText })).digest('hex');
     if (current.messageId && current.imageHash === hash) {
@@ -81,7 +82,7 @@ export function createLiveDiscord(db: AppDatabase, auth: ReturnType<typeof creat
         guildId = channel.guild_id;
       } catch { update(id, { status: 'error', error: 'Could not reach the Discord channel. Try again.' }); return; }
     }
-    const png = await renderLiveCard(data, current.theme);
+    const png = await renderLiveCard(data, current.theme, id);
     if (png.byteLength > 4 * 1024 * 1024) { update(id, { status: 'error', error: 'The rendered image exceeds the 4 MB sharing limit.' }); return; }
     // A stop or account deletion during image generation cancels the outbound edit.
     if (stopped || !['active', 'sending'].includes(row(id)?.status ?? '')) return;
@@ -139,7 +140,11 @@ export function createLiveDiscord(db: AppDatabase, auth: ReturnType<typeof creat
     clearTimeout(timers.get(id)); timers.delete(id);
     const existing = running.get(id);
     if (existing) return existing;
-    const work = queue.then(() => deliver(id)).catch(() => {
+    const work = queue.then(() => deliver(id)).catch(error => {
+      if (error instanceof RenderBusyError && !stopped && ['active', 'sending'].includes(row(id)?.status ?? '')) {
+        update(id, { dirty: true, retryAt: now() + 1000, error: 'Image rendering is busy; update queued.' });
+        schedule(id, 1000); return;
+      }
       if (!stopped && row(id)) { update(id, { status: 'error', error: 'Could not render or update the card. Try resuming updates.' }); }
     }).finally(() => running.delete(id));
     queue = work; running.set(id, work); return work;
@@ -152,7 +157,7 @@ export function createLiveDiscord(db: AppDatabase, auth: ReturnType<typeof creat
   app.get('/', c => c.json(state(c.get('user').id)));
   app.get('/preview', async c => {
     const theme = c.req.query('theme') === 'dark' ? 'dark' : 'light';
-    const image = await renderLiveCard(liveCardData(db, c.get('user').id, now()), theme);
+    const image = await renderLiveCard(await loadLiveCardData(db, c.get('user').id, now), theme, c.get('user').id);
     c.header('Content-Type', 'image/png'); c.header('Content-Disposition', 'inline; filename="minabot-live-progress.png"');
     return c.body(new Uint8Array(image));
   });

src/sharing/routes.ts

@@ -78,17 +78,19 @@ export function createSharingRoutes(db: AppDatabase, auth: ReturnType<typeof cre
 
   app.post("/preview", async c => {
     const input = await json(c.req.raw, shareInput);
-    const service = new HabitService(db, c.get("user"), now()); service.sync();
+    const result = await HabitService.withPrepared(db, c.get("user"), now, service => {
-    if (input.to > service.today) throw new ApiError(422, "The end date cannot be after today.");
+      if (input.to > service.today) throw new ApiError(422, "The end date cannot be after today.");
-    const result: ShareData = { from: input.from, to: input.to, timezone: service.user.timezone, habits: input.habitIds.map(id => {
+      const result: ShareData = { from: input.from, to: input.to, timezone: service.user.timezone, habits: input.habitIds.map(id => {
-      const habit = service.current(id);
+        const habit = service.current(id);
-      const chart = service.calendar([id], input.from, input.to, service.settings(id), false);
+        const chart = service.calendar([id], input.from, input.to, service.settings(id), false);
-      return { name: habit.name, color: chart.settings.mainColor,
+        return { name: habit.name, color: chart.settings.mainColor,
-        legend: { empty: chart.settings.emptyColor, complete: chart.settings.mainColor,
+          legend: { empty: chart.settings.emptyColor, complete: chart.settings.mainColor,
-          partial: chart.days.some(d => d.shadeCount > 1) ? [0.25, 0.5, 0.75].map(ratio => shade(ratio, 4, chart.settings, false).color) : [] },
+            partial: chart.days.some(d => d.shadeCount > 1) ? [0.25, 0.5, 0.75].map(ratio => shade(ratio, 4, chart.settings, false).color) : [] },
-        completed: chart.days.filter(d => d.completed > 0).length, scheduled: chart.days.filter(d => d.due > 0).length,
+          completed: chart.days.filter(d => d.completed > 0).length, scheduled: chart.days.filter(d => d.due > 0).length,
-        days: chart.days.map(d => ({ date: d.date, color: d.color, due: d.due > 0, complete: d.completed > 0, ratio: d.ratio })) };
+          days: chart.days.map(d => ({ date: d.date, color: d.color, due: d.due > 0, complete: d.completed > 0, ratio: d.ratio })) };
-    }) };
+      }) };
+      return result;
+    });
     result.botAvatarUrl = await botAvatarUrl();
     return c.json(result);
   });

styles/design-system.css

@@ -1,34 +1,34 @@
 @font-face {
   font-family: "Mina Sans";
-  src: url("../src/assets/fonts/NotoSans-Regular.ttf") format("truetype");
+  src: url("/fonts/browser/NotoSans-Regular.woff2") format("woff2");
   font-style: normal;
   font-weight: 400;
   font-display: swap;
 }
 @font-face {
   font-family: "Mina Sans";
-  src: url("../src/assets/fonts/NotoSans-Medium.ttf") format("truetype");
+  src: url("/fonts/browser/NotoSans-Medium.woff2") format("woff2");
   font-style: normal;
   font-weight: 500;
   font-display: swap;
 }
 @font-face {
   font-family: "Mina Sans";
-  src: url("../src/assets/fonts/NotoSans-SemiBold.ttf") format("truetype");
+  src: url("/fonts/browser/NotoSans-SemiBold.woff2") format("woff2");
   font-style: normal;
   font-weight: 600;
   font-display: swap;
 }
 @font-face {
   font-family: "Instrument Serif";
-  src: url("../src/assets/fonts/InstrumentSerif-Regular.ttf") format("truetype");
+  src: url("/fonts/browser/InstrumentSerif-Regular.woff2") format("woff2");
   font-weight: 400;
   font-style: normal;
   font-display: swap;
 }
 @font-face {
   font-family: "Instrument Serif";
-  src: url("../src/assets/fonts/InstrumentSerif-Italic.ttf") format("truetype");
+  src: url("/fonts/browser/InstrumentSerif-Italic.woff2") format("woff2");
   font-weight: 400;
   font-style: italic;
   font-display: swap;