diff --git a/drizzle/0003_finalize_occurrence_deadlines.sql b/drizzle/0003_finalize_occurrence_deadlines.sql
new file mode 100644
index 0000000..524232a
--- /dev/null
+++ b/drizzle/0003_finalize_occurrence_deadlines.sql
@@ -0,0 +1,17 @@
+ALTER TABLE `task_occurrences` ADD `closed_at` integer;--> statement-breakpoint
+-- Recover the state at the deadline from the first correction after it, when present.
+-- This also repairs expiry previously inferred from an uncheck made after completion.
+UPDATE task_occurrences
+SET closed_at = (SELECT ends_at FROM habit_days WHERE id = task_occurrences.day_id),
+    expired_at = CASE WHEN COALESCE(
+      (SELECT json_extract(e.before, '$.done') FROM progress_events e
+       WHERE e.occurrence_id = task_occurrences.id
+         AND e.created_at >= (SELECT ends_at FROM habit_days WHERE id = task_occurrences.day_id)
+       ORDER BY e.created_at, e.id LIMIT 1), done) = 0
+      THEN (SELECT ends_at FROM habit_days WHERE id = task_occurrences.day_id)
+      ELSE NULL END
+WHERE day_id IN (
+  SELECT d.id FROM habit_days d
+  WHERE d.ends_at <= CAST(unixepoch('subsec') * 1000 AS INTEGER)
+    AND d.id = (SELECT MAX(d2.id) FROM habit_days d2 WHERE d2.habit_id = d.habit_id AND d2.date = d.date)
+);
diff --git a/drizzle/meta/0003_snapshot.json b/drizzle/meta/0003_snapshot.json
new file mode 100644
index 0000000..6c6df77
--- /dev/null
+++ b/drizzle/meta/0003_snapshot.json
@@ -0,0 +1,691 @@
+{
+  "version": "6",
+  "dialect": "sqlite",
+  "id": "0893a83a-3004-440a-8e89-3a30f26a578d",
+  "prevId": "79583aaf-5f48-44cd-b105-407d229c3ced",
+  "tables": {
+    "combined_charts": {
+      "name": "combined_charts",
+      "columns": {
+        "id": {
+          "name": "id",
+          "type": "text",
+          "primaryKey": true,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "user_id": {
+          "name": "user_id",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "name": {
+          "name": "name",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "habit_ids": {
+          "name": "habit_ids",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "settings": {
+          "name": "settings",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "created_at": {
+          "name": "created_at",
+          "type": "integer",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "updated_at": {
+          "name": "updated_at",
+          "type": "integer",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        }
+      },
+      "indexes": {
+        "combined_charts_user_idx": {
+          "name": "combined_charts_user_idx",
+          "columns": [
+            "user_id"
+          ],
+          "isUnique": false
+        }
+      },
+      "foreignKeys": {
+        "combined_charts_user_id_users_id_fk": {
+          "name": "combined_charts_user_id_users_id_fk",
+          "tableFrom": "combined_charts",
+          "tableTo": "users",
+          "columnsFrom": [
+            "user_id"
+          ],
+          "columnsTo": [
+            "id"
+          ],
+          "onDelete": "no action",
+          "onUpdate": "no action"
+        }
+      },
+      "compositePrimaryKeys": {},
+      "uniqueConstraints": {},
+      "checkConstraints": {}
+    },
+    "habit_calendar_settings": {
+      "name": "habit_calendar_settings",
+      "columns": {
+        "habit_id": {
+          "name": "habit_id",
+          "type": "text",
+          "primaryKey": true,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "settings": {
+          "name": "settings",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        }
+      },
+      "indexes": {},
+      "foreignKeys": {
+        "habit_calendar_settings_habit_id_habits_id_fk": {
+          "name": "habit_calendar_settings_habit_id_habits_id_fk",
+          "tableFrom": "habit_calendar_settings",
+          "tableTo": "habits",
+          "columnsFrom": [
+            "habit_id"
+          ],
+          "columnsTo": [
+            "id"
+          ],
+          "onDelete": "no action",
+          "onUpdate": "no action"
+        }
+      },
+      "compositePrimaryKeys": {},
+      "uniqueConstraints": {},
+      "checkConstraints": {}
+    },
+    "habit_days": {
+      "name": "habit_days",
+      "columns": {
+        "id": {
+          "name": "id",
+          "type": "integer",
+          "primaryKey": true,
+          "notNull": true,
+          "autoincrement": true
+        },
+        "habit_id": {
+          "name": "habit_id",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "revision_id": {
+          "name": "revision_id",
+          "type": "integer",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "date": {
+          "name": "date",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "timezone": {
+          "name": "timezone",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "ends_at": {
+          "name": "ends_at",
+          "type": "integer",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "count_set": {
+          "name": "count_set",
+          "type": "integer",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false,
+          "default": false
+        },
+        "count": {
+          "name": "count",
+          "type": "integer",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false,
+          "default": 0
+        },
+        "done": {
+          "name": "done",
+          "type": "integer",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false,
+          "default": false
+        }
+      },
+      "indexes": {
+        "habit_days_lookup_idx": {
+          "name": "habit_days_lookup_idx",
+          "columns": [
+            "habit_id",
+            "date",
+            "revision_id"
+          ],
+          "isUnique": false
+        }
+      },
+      "foreignKeys": {
+        "habit_days_habit_id_habits_id_fk": {
+          "name": "habit_days_habit_id_habits_id_fk",
+          "tableFrom": "habit_days",
+          "tableTo": "habits",
+          "columnsFrom": [
+            "habit_id"
+          ],
+          "columnsTo": [
+            "id"
+          ],
+          "onDelete": "no action",
+          "onUpdate": "no action"
+        },
+        "habit_days_revision_id_habit_revisions_id_fk": {
+          "name": "habit_days_revision_id_habit_revisions_id_fk",
+          "tableFrom": "habit_days",
+          "tableTo": "habit_revisions",
+          "columnsFrom": [
+            "revision_id"
+          ],
+          "columnsTo": [
+            "id"
+          ],
+          "onDelete": "no action",
+          "onUpdate": "no action"
+        }
+      },
+      "compositePrimaryKeys": {},
+      "uniqueConstraints": {},
+      "checkConstraints": {}
+    },
+    "habit_revisions": {
+      "name": "habit_revisions",
+      "columns": {
+        "id": {
+          "name": "id",
+          "type": "integer",
+          "primaryKey": true,
+          "notNull": true,
+          "autoincrement": true
+        },
+        "habit_id": {
+          "name": "habit_id",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "effective_date": {
+          "name": "effective_date",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "config": {
+          "name": "config",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "created_at": {
+          "name": "created_at",
+          "type": "integer",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        }
+      },
+      "indexes": {
+        "habit_revisions_date_idx": {
+          "name": "habit_revisions_date_idx",
+          "columns": [
+            "habit_id",
+            "effective_date",
+            "id"
+          ],
+          "isUnique": false
+        }
+      },
+      "foreignKeys": {
+        "habit_revisions_habit_id_habits_id_fk": {
+          "name": "habit_revisions_habit_id_habits_id_fk",
+          "tableFrom": "habit_revisions",
+          "tableTo": "habits",
+          "columnsFrom": [
+            "habit_id"
+          ],
+          "columnsTo": [
+            "id"
+          ],
+          "onDelete": "no action",
+          "onUpdate": "no action"
+        }
+      },
+      "compositePrimaryKeys": {},
+      "uniqueConstraints": {},
+      "checkConstraints": {}
+    },
+    "habits": {
+      "name": "habits",
+      "columns": {
+        "id": {
+          "name": "id",
+          "type": "text",
+          "primaryKey": true,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "user_id": {
+          "name": "user_id",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "created_date": {
+          "name": "created_date",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "materialized_through": {
+          "name": "materialized_through",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": false,
+          "autoincrement": false
+        },
+        "created_at": {
+          "name": "created_at",
+          "type": "integer",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        }
+      },
+      "indexes": {
+        "habits_user_idx": {
+          "name": "habits_user_idx",
+          "columns": [
+            "user_id"
+          ],
+          "isUnique": false
+        }
+      },
+      "foreignKeys": {
+        "habits_user_id_users_id_fk": {
+          "name": "habits_user_id_users_id_fk",
+          "tableFrom": "habits",
+          "tableTo": "users",
+          "columnsFrom": [
+            "user_id"
+          ],
+          "columnsTo": [
+            "id"
+          ],
+          "onDelete": "no action",
+          "onUpdate": "no action"
+        }
+      },
+      "compositePrimaryKeys": {},
+      "uniqueConstraints": {},
+      "checkConstraints": {}
+    },
+    "progress_events": {
+      "name": "progress_events",
+      "columns": {
+        "id": {
+          "name": "id",
+          "type": "integer",
+          "primaryKey": true,
+          "notNull": true,
+          "autoincrement": true
+        },
+        "day_id": {
+          "name": "day_id",
+          "type": "integer",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "occurrence_id": {
+          "name": "occurrence_id",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": false,
+          "autoincrement": false
+        },
+        "before": {
+          "name": "before",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "after": {
+          "name": "after",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "created_at": {
+          "name": "created_at",
+          "type": "integer",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        }
+      },
+      "indexes": {
+        "progress_events_day_idx": {
+          "name": "progress_events_day_idx",
+          "columns": [
+            "day_id"
+          ],
+          "isUnique": false
+        }
+      },
+      "foreignKeys": {
+        "progress_events_day_id_habit_days_id_fk": {
+          "name": "progress_events_day_id_habit_days_id_fk",
+          "tableFrom": "progress_events",
+          "tableTo": "habit_days",
+          "columnsFrom": [
+            "day_id"
+          ],
+          "columnsTo": [
+            "id"
+          ],
+          "onDelete": "no action",
+          "onUpdate": "no action"
+        }
+      },
+      "compositePrimaryKeys": {},
+      "uniqueConstraints": {},
+      "checkConstraints": {}
+    },
+    "sessions": {
+      "name": "sessions",
+      "columns": {
+        "token_hash": {
+          "name": "token_hash",
+          "type": "text",
+          "primaryKey": true,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "user_id": {
+          "name": "user_id",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "created_at": {
+          "name": "created_at",
+          "type": "integer",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "expires_at": {
+          "name": "expires_at",
+          "type": "integer",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        }
+      },
+      "indexes": {
+        "sessions_user_id_idx": {
+          "name": "sessions_user_id_idx",
+          "columns": [
+            "user_id"
+          ],
+          "isUnique": false
+        },
+        "sessions_expires_at_idx": {
+          "name": "sessions_expires_at_idx",
+          "columns": [
+            "expires_at"
+          ],
+          "isUnique": false
+        }
+      },
+      "foreignKeys": {
+        "sessions_user_id_users_id_fk": {
+          "name": "sessions_user_id_users_id_fk",
+          "tableFrom": "sessions",
+          "tableTo": "users",
+          "columnsFrom": [
+            "user_id"
+          ],
+          "columnsTo": [
+            "id"
+          ],
+          "onDelete": "cascade",
+          "onUpdate": "no action"
+        }
+      },
+      "compositePrimaryKeys": {},
+      "uniqueConstraints": {},
+      "checkConstraints": {}
+    },
+    "task_occurrences": {
+      "name": "task_occurrences",
+      "columns": {
+        "id": {
+          "name": "id",
+          "type": "text",
+          "primaryKey": true,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "day_id": {
+          "name": "day_id",
+          "type": "integer",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "task_id": {
+          "name": "task_id",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "name": {
+          "name": "name",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "done": {
+          "name": "done",
+          "type": "integer",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false,
+          "default": false
+        },
+        "expired_at": {
+          "name": "expired_at",
+          "type": "integer",
+          "primaryKey": false,
+          "notNull": false,
+          "autoincrement": false
+        },
+        "closed_at": {
+          "name": "closed_at",
+          "type": "integer",
+          "primaryKey": false,
+          "notNull": false,
+          "autoincrement": false
+        },
+        "updated_at": {
+          "name": "updated_at",
+          "type": "integer",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        }
+      },
+      "indexes": {
+        "task_occurrences_day_idx": {
+          "name": "task_occurrences_day_idx",
+          "columns": [
+            "day_id"
+          ],
+          "isUnique": false
+        }
+      },
+      "foreignKeys": {
+        "task_occurrences_day_id_habit_days_id_fk": {
+          "name": "task_occurrences_day_id_habit_days_id_fk",
+          "tableFrom": "task_occurrences",
+          "tableTo": "habit_days",
+          "columnsFrom": [
+            "day_id"
+          ],
+          "columnsTo": [
+            "id"
+          ],
+          "onDelete": "no action",
+          "onUpdate": "no action"
+        }
+      },
+      "compositePrimaryKeys": {},
+      "uniqueConstraints": {},
+      "checkConstraints": {}
+    },
+    "users": {
+      "name": "users",
+      "columns": {
+        "id": {
+          "name": "id",
+          "type": "text",
+          "primaryKey": true,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "discord_id": {
+          "name": "discord_id",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "username": {
+          "name": "username",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "global_name": {
+          "name": "global_name",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": false,
+          "autoincrement": false
+        },
+        "avatar_hash": {
+          "name": "avatar_hash",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": false,
+          "autoincrement": false
+        },
+        "timezone": {
+          "name": "timezone",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false,
+          "default": "'UTC'"
+        },
+        "created_at": {
+          "name": "created_at",
+          "type": "integer",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        },
+        "updated_at": {
+          "name": "updated_at",
+          "type": "integer",
+          "primaryKey": false,
+          "notNull": true,
+          "autoincrement": false
+        }
+      },
+      "indexes": {
+        "users_discord_id_unique": {
+          "name": "users_discord_id_unique",
+          "columns": [
+            "discord_id"
+          ],
+          "isUnique": true
+        }
+      },
+      "foreignKeys": {},
+      "compositePrimaryKeys": {},
+      "uniqueConstraints": {},
+      "checkConstraints": {}
+    }
+  },
+  "views": {},
+  "enums": {},
+  "_meta": {
+    "schemas": {},
+    "tables": {},
+    "columns": {}
+  },
+  "internal": {
+    "indexes": {}
+  }
+}
\ No newline at end of file
diff --git a/drizzle/meta/_journal.json b/drizzle/meta/_journal.json
index e40c063..f3b744f 100644
--- a/drizzle/meta/_journal.json
+++ b/drizzle/meta/_journal.json
@@ -22,6 +22,13 @@
       "when": 1788505800600,
       "tag": "0002_optional_count_carryover",
       "breakpoints": true
+    },
+    {
+      "idx": 3,
+      "version": "6",
+      "when": 1788507928967,
+      "tag": "0003_finalize_occurrence_deadlines",
+      "breakpoints": true
     }
   ]
 }
\ No newline at end of file
diff --git a/src/db/migrations.test.ts b/src/db/migrations.test.ts
index 4aa0612..c6f6482 100644
--- a/src/db/migrations.test.ts
+++ b/src/db/migrations.test.ts
@@ -27,3 +27,27 @@ test('carryover migration preserves pre-existing counts and explicit zero correc
     expect(JSON.parse(config).carryPartialProgress).toBe(false);
   } finally { sqlite.close(); rmSync(directory, { recursive: true, force: true }); }
 });
+
+test('deadline migration repairs historical expiry using the original state before corrections', () => {
+  const directory = mkdtempSync(join(tmpdir(), 'minabot-expiry-upgrade-'));
+  const sqlite = new Database(':memory:'); const db = drizzle(sqlite);
+  try {
+    mkdirSync(join(directory, 'meta'));
+    const journal = JSON.parse(readFileSync('drizzle/meta/_journal.json', 'utf8'));
+    journal.entries = journal.entries.slice(0, 3);
+    writeFileSync(join(directory, 'meta/_journal.json'), JSON.stringify(journal));
+    for (const entry of journal.entries) copyFileSync(`drizzle/${entry.tag}.sql`, join(directory, `${entry.tag}.sql`));
+    migrate(db, { migrationsFolder: directory });
+    sqlite.exec("INSERT INTO users (id, discord_id, username, created_at, updated_at) VALUES ('u', 'u', 'u', 0, 0)");
+    sqlite.exec("INSERT INTO habits (id, user_id, created_date, created_at) VALUES ('h', 'u', '2020-01-01', 0)");
+    sqlite.query('INSERT INTO habit_revisions (habit_id, effective_date, config, created_at) VALUES (?, ?, ?, ?)').run('h', '2020-01-01', JSON.stringify({ name: 'Tasks', method: 'tasks', tasks: [], schedule: { type: 'daily' }, archived: false }), 0);
+    sqlite.exec("INSERT INTO habit_days (habit_id, revision_id, date, timezone, ends_at) VALUES ('h', 1, '2020-01-01', 'UTC', 100)");
+    sqlite.exec("INSERT INTO task_occurrences (id, day_id, task_id, name, done, expired_at, updated_at) VALUES ('a', 1, 'a', 'Originally completed', 0, 100, 200), ('b', 1, 'b', 'Originally incomplete', 1, 100, 200)");
+    sqlite.query('INSERT INTO progress_events (day_id, occurrence_id, before, after, created_at) VALUES (?, ?, ?, ?, ?)').run(1, 'a', '{"done":true}', '{"done":false}', 200);
+    sqlite.query('INSERT INTO progress_events (day_id, occurrence_id, before, after, created_at) VALUES (?, ?, ?, ?, ?)').run(1, 'b', '{"done":false}', '{"done":true}', 200);
+    migrate(db, { migrationsFolder: './drizzle' });
+    expect(sqlite.query('SELECT id, expired_at, closed_at, done FROM task_occurrences ORDER BY id').all()).toEqual([
+      { id: 'a', expired_at: null, closed_at: 100, done: 0 }, { id: 'b', expired_at: 100, closed_at: 100, done: 1 },
+    ]);
+  } finally { sqlite.close(); rmSync(directory, { recursive: true, force: true }); }
+});
diff --git a/src/db/schema.ts b/src/db/schema.ts
index 0bcfd02..98be8bf 100644
--- a/src/db/schema.ts
+++ b/src/db/schema.ts
@@ -37,7 +37,7 @@ export const habitDays = sqliteTable('habit_days', {
 }, t => [index('habit_days_lookup_idx').on(t.habitId, t.date, t.revisionId)]);
 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'), updatedAt: integer('updated_at').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)]);
 export const progressEvents = sqliteTable('progress_events', {
   id: integer('id').primaryKey({ autoIncrement: true }), dayId: integer('day_id').notNull().references(() => habitDays.id), occurrenceId: text('occurrence_id'),
diff --git a/src/habits/regressions.test.ts b/src/habits/regressions.test.ts
index b103f8e..c36f20f 100644
--- a/src/habits/regressions.test.ts
+++ b/src/habits/regressions.test.ts
@@ -18,3 +18,34 @@ test('chart PATCH preserves omitted settings and rejects an empty patch', async
   expect((await f.request(`/charts/${c.id}`, 'PATCH', {})).status).toBe(422);
   expect((await f.json(`/charts/${c.id}`, 'PATCH', { settings: {} })).settings.mainColor).toBe('#196127');
 });
+test('archiving and restoring retains same-day task states and combined completion', async () => {
+  const h = await taskHabit(); await tick(h, true);
+  const c = await f.json('/charts', 'POST', { name: 'Combined', habitIds: [h.id] }, 201);
+  await f.request(`/habits/${h.id}`, 'DELETE');
+  expect((await detail(h.id)).due).toBe(false);
+  await f.json(`/habits/${h.id}`, 'PATCH', { archived: false });
+  expect((await detail(h.id)).value).toBe(1);
+  expect((await f.json(`/charts/${c.id}/days/2026-09-04`)).ratio).toBe(1);
+  await tick(h, false); await f.request(`/habits/${h.id}`, 'DELETE'); await f.json(`/habits/${h.id}`, 'PATCH', { archived: false });
+  expect((await detail(h.id)).value).toBe(0);
+});
+test('temporarily disabling the schedule retains same-day occurrence progress', async () => {
+  const h = await taskHabit(); await tick(h, true);
+  await f.json(`/habits/${h.id}`, 'PATCH', { schedule: { type: 'weekdays', days: [1] } });
+  await f.json(`/habits/${h.id}`, 'PATCH', { schedule: { type: 'daily' } });
+  expect((await detail(h.id)).value).toBe(1);
+});
+test('post-deadline corrections never invent expiry for an originally completed occurrence', async () => {
+  const h = await taskHabit(); await tick(h, true); f.setTime('2026-09-05T12:00Z');
+  expect((await detail(h.id)).tasks[0].expiredAt).toBeNull();
+  await tick(h, false);
+  for (let i = 0; i < 2; i++) expect((await detail(h.id)).tasks[0].expiredAt).toBeNull();
+  await tick(h, true); expect((await detail(h.id)).tasks[0].expiredAt).toBeNull();
+});
+test('expired occurrences preserve original expiry through repeated historical corrections', async () => {
+  const h = await taskHabit(); f.setTime('2026-09-05T12:00Z');
+  const expired = (await detail(h.id)).tasks[0].expiredAt;
+  expect(expired).toBe(Date.parse('2026-09-04T22:00Z'));
+  await tick(h, true); expect((await detail(h.id)).tasks[0].expiredAt).toBe(expired);
+  await tick(h, false); expect((await detail(h.id)).tasks[0].expiredAt).toBe(expired);
+});
diff --git a/src/habits/service.ts b/src/habits/service.ts
index 4f1a3e2..004ccc1 100644
--- a/src/habits/service.ts
+++ b/src/habits/service.ts
@@ -104,8 +104,10 @@ export class HabitService {
     this.db.transaction(() => {
       for (const habit of this.db.select().from(habits).where(eq(habits.userId, this.user.id)).all()) this.materialize(habit);
       // Record the original deadline even after downtime. Only active day snapshots expire.
-      this.db.run(sql`UPDATE task_occurrences SET expired_at = (SELECT ends_at FROM habit_days WHERE id = task_occurrences.day_id)
-        WHERE done = 0 AND expired_at IS NULL AND day_id IN (
+      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 (
           SELECT d.id FROM habit_days d JOIN habits h ON h.id = d.habit_id
           WHERE 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))`);
@@ -150,11 +152,16 @@ export class HabitService {
           timezone: existing?.timezone ?? this.user.timezone, endsAt: existing?.endsAt ?? this.deadline(date),
           countSet: existing && !sameMethod && revision.config.method === 'count' ? true : sameMethod ? existing!.countSet : false, count: sameMethod ? existing!.count : 0, done: sameMethod ? existing!.done : false }).returning().get();
         if (revision.config.method === 'tasks' && !revision.config.archived && scheduled(revision.config.schedule, date)) {
-          const previous = existing ? this.db.select().from(taskOccurrences).where(eq(taskOccurrences.dayId, existing.id)).all() : [];
+          // A temporary archive or schedule change can leave the immediately prior snapshot empty.
+          // Stable task IDs recover the latest occurrence from this date only.
+          const previous = existing ? this.db.select({ occurrence: taskOccurrences }).from(taskOccurrences)
+            .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 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,
-              done: old?.done ?? false, expiredAt: old?.expiredAt ?? (day.endsAt <= this.now && !old?.done ? day.endsAt : null), updatedAt: this.now }).run();
+              done: old?.done ?? false, expiredAt: old?.expiredAt ?? (day.endsAt <= this.now && !old?.done ? day.endsAt : null), closedAt: old?.closedAt ?? (day.endsAt <= this.now ? day.endsAt : null), updatedAt: old?.updatedAt ?? this.now }).run();
           }
         }
       }
@@ -187,7 +194,7 @@ export class HabitService {
     const future = date > this.today;
     const tasks = config?.method === 'tasks' && !config.archived && scheduled(config.schedule, date)
       ? record ? this.occurrences(id).get(record.id) ?? []
-        : config.tasks.filter(t => scheduled(t.schedule, date)).map(t => ({ id: null, taskId: t.id, name: t.name, done: false, expiredAt: null, updatedAt: null })) : [];
+        : config.tasks.filter(t => scheduled(t.schedule, date)).map(t => ({ id: null, taskId: t.id, name: t.name, done: false, expiredAt: null, closedAt: null, updatedAt: null })) : [];
     const due = !!config && !config.archived && scheduled(config.schedule, date) && (config.method !== 'tasks' || tasks.length > 0);
     const counted = config?.method === 'count' && !future ? this.counts(id).get(date) : undefined;
     const value = !due ? 0 : config!.method === 'count' ? counted?.value ?? 0 : config!.method === 'manual' ? Number(record?.done ?? false) : tasks.filter(t => t.done).length;