fix(server): drop V1 projections nothing reads after the V2 upgrade

[juliusmarminge]

Upgrading to 0.1.0 starts statev2.sqlite as a full copy of the V1 database. V2 never reads six of those V1 tables, so long-time users keep them forever: 5.9 GiB in #20922, mostly the old activity log.

Migration 63 drops projection_thread_activities, projection_turns, projection_thread_proposed_plans, projection_pending_approvals, projection_state and checkpoint_diff_blobs. Nothing on main or in 0.1.0 reads them outside migrations and tests. The V1 transcript import still reads threads, messages and pull request links, so those tables stay. Builds before 0.1.0 read state.sqlite, never this file, so rolling back is unaffected.

Dropping only frees pages, which is quick: 696 MiB dropped in 168 ms. Upgraded databases have auto_vacuum off, so those pages count as reclaimable space. The Settings notice from #19437 suggests t3 doctor at 1 GiB, and its existing "Reclaim database space" repair returns them to disk.

The mobile showcase seed still wrote into these tables and waited for them to exist. Those rows were never shown by V2 clients (#15013), so the seed no longer writes them.

Verification

Migration test: the six tables are gone, while the transcript import tables and their rows are kept. The V1 cutover integration test and the showcase test still pass.

On a copy of a real 8.58 GiB V2 database, a normal server start ran migration 63:

before: Database: 8.58 GiB, 0 KiB reclaimable.
after:  Database: 8.58 GiB, 694.9 MiB reclaimable.

Part of #20922. #20948 adds the opt-in repair for the V1 file itself.

🤖 Generated with Claude Code

Closes #20922

[macroscopeapp]

Approvability

Verdict: Needs Human Approval

Macroscope's review found this PR requires human approval — The upgrade now automatically deletes six existing SQLite tables and their stored rows, while the other changes update tests and a development showcase seed. Although the migration is tested and intended tables are obsolete, its irreversible production data/schema impact warrants deliberate review.

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[github-actions]

Thread transfer impact

✅ Thread transfer remains within every enforced ceiling.

Provider	Metric	Main baseline	This PR	Impact	PR ceiling
Codex	Total thread wire	5.0 KiB	5.0 KiB	+7 B (+0.1%)	6.8 KiB	✅
Codex	Thread snapshot wire	3.8 KiB	3.8 KiB	0 B (0.0%)	4.9 KiB	✅
Codex	Live turn WebSocket wire	1.2 KiB	1.2 KiB	+7 B (+0.6%)	2.0 KiB	✅
Codex	Live turn WebSocket decoded	20.9 KiB	20.9 KiB	0 B (0.0%)	29.3 KiB	✅
Codex	Live turn messages	2	2	0 (0.0%)	8	✅
Claude	Total thread wire	5.0 KiB	5.0 KiB	0 B (0.0%)	6.8 KiB	✅
Claude	Thread snapshot wire	3.8 KiB	3.8 KiB	0 B (0.0%)	4.9 KiB	✅
Claude	Live turn WebSocket wire	1.2 KiB	1.2 KiB	0 B (0.0%)	2.0 KiB	✅
Claude	Live turn WebSocket decoded	21.2 KiB	21.2 KiB	0 B (0.0%)	29.3 KiB	✅
Claude	Live turn messages	2	2	0 (0.0%)	8	✅

Baseline: 4b1024d · PR result: e910922 · Source CI: success

Scenario and decoded snapshot size

10 historical turns, 5 command tools per turn, 878.9 KiB retained MCP result per historical turn, and a 1.05 MiB retained result in the measured turn.

• Codex decoded thread snapshot: 108.5 KiB
• Claude decoded thread snapshot: 108.8 KiB

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📥 Commits

Reviewing files that changed from the base of the PR and between 4b1024d and e910922.

📒 Files selected for processing: 6

• apps/server/src/persistence/Migrations.ts
• apps/server/src/persistence/Migrations/055_OrchestrationV2.test.ts
• apps/server/src/persistence/Migrations/063_DropUnusedV1Projections.test.ts
• apps/server/src/persistence/Migrations/063_DropUnusedV1Projections.ts
• apps/server/src/persistence/reconcileV2PreviewMigration.test.ts
• scripts/mobile-showcase-environment.ts

💤 Files with no reviewable changes: 1

• scripts/mobile-showcase-environment.ts

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📝 Walkthrough

Migration 63 drops six projection tables and is added to migration registration and upgrade expectations. Migration tests check that transcript tables and message data remain. The mobile showcase seed no longer creates or clears the removed projection data.

Changes: V1 Projection Cleanup

Layer / File(s)	Summary
Register and verify migration 63 apps/server/src/persistence/Migrations/063_DropUnusedV1Projections.ts, apps/server/src/persistence/Migrations.ts, apps/server/src/persistence/Migrations/063_DropUnusedV1Projections.test.ts, apps/server/src/persistence/Migrations/055_OrchestrationV2.test.ts, apps/server/src/persistence/reconcileV2PreviewMigration.test.ts	Migration 63 drops six tables if they exist. Registration and upgrade expectations include the migration. Its test checks that three transcript-related tables and an inserted message remain.
Update mobile showcase seeding scripts/mobile-showcase-environment.ts	The seed no longer inserts projection turns, activity records, or projection-state rows. Its cleanup list now includes only thread messages, thread sessions, and threads.

Priority: ➖ Normal

Estimated code review effort: 2 (Simple) | ~12 minutes

Change: Bug fix

Suggested reviewers: realhasanshoaib, maria-rcks

Merge Risk: ⚪ Minimal · up to e9109

The change drops unused V1 tables so upgraded databases can reclaim space. No remaining code path reads those tables, and the transcript import tables are kept. No merge-blocking risk was found.

Pre-merge checks: 4

Check name	Status	Explanation
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.
Title check		The title clearly and concisely describes the main change: removing unused V1 projections after the V2 upgrade.
Description check		The description explains the problem, the migration changes, retained tables, scope, issue references, rollback impact, and focused verification results. It is sufficiently complete despite not using …

Full details: Description check

Explanation

The description explains the problem, the migration changes, retained tables, scope, issue references, rollback impact, and focused verification results. It is sufficiently complete despite not using all template headings explicitly.

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