test(e2e): enable Playwright parallelization (TST-60, #867)

[Chris0Jeky]

Summary

• Switch Playwright E2E suite from serial to parallel: fullyParallel: true
• CI workers default to 2 (was 1), overridable via TASKDECK_E2E_WORKERS
• Tighten E2E SQLite connection string with Cache=Shared;Pooling=True;Default Timeout=30 so concurrent writes wait on the busy lock instead of surfacing SQLITE_BUSY under bursty parallel traffic
• Single-file diff: frontend/taskdeck-web/playwright.config.ts

Why this is safe

Per-test isolation is already in place at the data layer: registerUserSession (tests/e2e/support/authSession.ts) provisions a unique user per test with Date.now() + random suffixes; board/column/card names follow the same pattern; data is scoped server-side by the authenticated user. Remaining contention is at the SQLite engine level, which the connection-string tweaks bound without altering on-disk format.

Test plan

• CI E2E Smoke lane is green on this PR
• No increase in flake rate across 2–3 consecutive CI runs
• Target: ≥40% wall-time reduction per the TST-60: Enable E2E test parallelization #867 acceptance criterion

Honest caveats

• Timing claim in commit message is unverified. The parent agent stalled before completing its final timing run; the "~half serial wall time" figure in the commit body should be validated against CI timing, not taken as-is. If CI does not confirm ≥40% reduction, additional tuning (worker count, backend connection pool) is follow-up.
• workers: undefined locally means Playwright's default (cores/2) — potentially higher parallelism than CI. If this drives flake locally, cap it.
• Default Timeout=30 maps to SqliteCommand.CommandTimeout in Microsoft.Data.Sqlite; it raises the effective busy-timeout envelope but is not a PRAGMA-level busy_timeout override. Validate with real CI traffic.

Refs

• Closes TST-60: Enable E2E test parallelization #867 (TST-60)
• Tracker PROD-00: Production readiness wave tracker (from 2026-04-16 audit) #881 (PROD-00 Tier 3)

[Chris0Jeky]

Critical adversarial self-review (author, TST-60)

The implementing agent stalled before its final run, so I (parent session) am doing this review with a cold eye. Running through the usual failure modes:

Checked — safe

1. Per-test user uniqueness. registerUserSession (tests/e2e/support/authSession.ts line 33) suffixes with ${Date.now()}-${Math.floor(Math.random() * 1_000_000)}. Even if two workers collide on Date.now() ms, the 1M random space gives ~1e-6 collision probability per pair — not zero, but bounded well below test-count scale.
2. Stakeholder demo opt-out. stakeholder-demo.spec.ts:208 guards with test.skip(!parseTrueishEnv(process.env.TASKDECK_RUN_DEMO), ...). Default-off; will not run in parallel with the regular suite.
3. Rate limiting (the obvious parallelization footgun). AuthPerIp is partitioned by IP and all workers share 127.0.0.1 — but appsettings.Development.json raises AuthPerIp.PermitLimit to 120/60s (vs 20/60s default). Two workers doing burst register+login cannot plausibly breach this. All other policies (HotPathPerUser, CaptureWritePerUser, TokenRefreshPerUser, NoteImportPerUser) partition by user ID → parallel-safe since every test has its own user.

Real caveats

1. Timing claim in the commit message is unverified. "~half serial wall time" in the commit body was written by an agent that did not complete its final timing run. The PR body already flags this. Validate against real CI timing, not the commit body. If the E2E Smoke lane does not show ≥40% reduction, that is a blocker for closing TST-60: Enable E2E test parallelization #867.
2. Local worker count is uncapped. workers: undefined locally means Playwright's default (cores/2) — on an 8-core dev box that is 4 workers, which could push AuthPerIp toward the 120/60s ceiling with hot loops. Not a CI issue. If developers hit 429s locally, set TASKDECK_E2E_WORKERS=2. Not fixing preemptively; documenting here is enough.
3. Default Timeout=30 semantics. This is the Microsoft.Data.Sqlite connection-string knob that sets SqliteCommand.CommandTimeout as the default. The provider applies it during command execution, which covers the busy-lock window in practice, but it is not a direct PRAGMA busy_timeout override. Behavior is correct for this use case; the mental model in the commit message slightly overclaims.
4. webServer.reuseExistingServer. Not touched by this PR. First-request bootstrap (migrations, seeds) should be a one-time op the backend serializes; if CI ever shows a startup race, the fix is in the backend startup path, not here.
5. Flake rate. Cannot verify in a single CI run — the acceptance criterion says "no increase in flake rate." Needs 2–3 consecutive green runs before we call this done. Worth re-queueing CI if the first run is a clean pass.

Verdict

Ship, but hold #867 open until CI shows: (a) green E2E Smoke, (b) measurable wall-time reduction against the pre-change baseline, (c) two additional re-runs with no new flake. I will not claim the acceptance criterion is met on a single green run.

No commit-level action needed from the review. Will act on (1)/(5) only if CI contradicts the current plan.

[gemini-code-assist]

Code Review

This pull request optimizes E2E test execution by enabling parallelization and tuning SQLite connection settings. Key changes include the introduction of a resolveWorkers utility to manage concurrency across environments and the configuration of connection strings with pooling and timeouts. Feedback suggests removing the Cache=Shared option from the SQLite connection string to avoid potential table-level locking issues, recommending Write-Ahead Logging (WAL) as a more performant alternative for concurrency.

[gemini-code-assist]

Using Cache=Shared (Shared-Cache Mode) is generally discouraged for modern SQLite applications. While it allows multiple connections to share a page cache, it introduces internal table-level locking that can actually increase contention and lead to more SQLITE_BUSY errors compared to the default private-cache mode. For optimal concurrency, it is better to use the default cache mode and enable Write-Ahead Logging (WAL) in the backend (e.g., via PRAGMA journal_mode=WAL; in the backend startup), while relying on the Default Timeout to handle transient locks. Please also update the documentation comment above this line if you remove this option.

Suggested change

	const e2eSqliteConnectionOptions = 'Cache=Shared;Pooling=True;Default Timeout=30'
	const e2eSqliteConnectionOptions = 'Pooling=True;Default Timeout=30'

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Bound local worker count for fully parallel runs

With fullyParallel: true, leaving workers unset makes local runs inherit Playwright’s default worker count (the CLI help reports this as 50% of logical CPU cores), so a developer machine can fan out far beyond the intended 2-worker contention budget against the single SQLite file/backend process. In non-CI environments where TASKDECK_E2E_WORKERS is not set, this turns parallelism into an unbounded local-flake source (SQLITE_BUSY/timeouts) rather than the controlled parallelization described in this change.

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[Chris0Jeky]

Round 2 adversarial review

Failure diagnosis (E2E Smoke)

Downloaded the playwright-test-results artifact from run 24837166919. One test failed of 146+13skipped: smoke.spec.ts:283 column WIP limit should reject additional cards. Error: locator.fill: Test timeout of 45000ms exceeded. waiting for locator('#wip-limit').

The page snapshot at failure time shows the Edit Column modal open and focused, but the #column-has-wip-limit checkbox was rendered without [checked] in the YAML (only [active], i.e. focused). The #wip-limit input is v-if="hasWipLimit" in ColumnEditModal.vue:141 — so the Vue reactive flag was false and the dependent input never rendered.

Root cause: latent race in the test exposed by parallel CPU contention. await checkbox.check() simulates a click and verifies DOM checked became true, then the test immediately called .fill('#wip-limit'). Under a 2-worker CI run on a 4-vCPU ubuntu-latest runner, Vue's v-model change handler can be preempted / delayed such that hasWipLimit never flipped to true and Vue later re-synchronized the checkbox DOM back to unchecked. The SQLite side was healthy — all queries in the log ran in 0–1ms, zero SQLITE_BUSY.

Cross-check: recent PRs on main (#936, #937, #938, #940) all passed E2E Smoke in 4–5 min. So the failure is not pre-existing — it is a flake triggered by the parallelization enabled in this PR.

Bot triage

gemini-code-assist[bot] medium (Cache=Shared on line 33) — valid and actioned. Shared-cache mode adds internal table-level locking that tends to increase SQLITE_BUSY in multi-threaded usage rather than reduce it, especially without WAL. The backend does not enable WAL, so dropping Cache=Shared is the right conservative default. Kept Pooling=True;Default Timeout=30 and documented WAL as future work. Not the cause of today's failure (logs show no lock pressure), but a real defensive improvement.

chatgpt-codex-connector[bot] P2 (unbounded local workers) — valid and actioned. With fullyParallel: true and workers: undefined locally, Playwright defaulted to ~50% of logical cores, fanning out far beyond the contention budget this config was tuned for. Changed the default to 2 workers everywhere (local and CI) and kept TASKDECK_E2E_WORKERS as the opt-in override for exploration.

New findings from this round

Test hygiene: the WIP smoke test relied on a synchronous assumption about Vue's checkbox v-model propagation that only held under serial execution. Any UI test that touches a control whose sibling DOM is v-if-gated on that control's state needs to wait for the dependent element, not the control itself. Worth a broader audit in a follow-up, but beyond this PR's scope.

Future work (not done here): enable PRAGMA journal_mode=WAL in the backend startup for real concurrent-read throughput. Would let us safely raise worker counts past 2.

Chosen path + rationale

Path 1 (tune and re-run) rather than backing out. Three small commits pushed:

1. 12ce18c6 — Fix the test (the actual root cause). Replace .check() + immediate .fill() with expect.poll that waits for #wip-limit to appear (re-clicking the checkbox if Vue's change event was swallowed), then asserts toBeChecked and fills. Fails fast with a clear message if propagation genuinely never completes.
2. cb6fb1c4 — Bound local workers (Codex P2). Default 2 everywhere, env override preserved. Renamed ciWorkerDefault → defaultWorkerCount.
3. 577eabd1 — Drop Cache=Shared (Gemini medium). Kept Pooling=True;Default Timeout=30, documented WAL as future follow-up.

Each passes npm run typecheck and npm run lint in frontend/taskdeck-web.

Verdict

Conditional approve. Fix is small, honest, and addresses the root cause rather than hiding it by lowering worker count to 1. Waiting on post-push CI run — if E2E Smoke goes green, this is ready to land. If a different test flakes next, the test-hygiene audit becomes the next priority. The 40%+ runtime reduction acceptance criterion for TST-60 is still expected to hold at 2 workers; measurement after the next green run.

[Chris0Jeky]

Round 2 follow-up — fallback to workers=1 in CI

Second CI pass with workers=2 hit the same smoke test but not the same race. The parent session (me, not the round-2 agent) inspected the new failure:

Failure: smoke.spec.ts:283 column WIP limit should reject additional cards — 45s test timeout on wipLimit.fill('1') (line 314). Playwright log:

Error: locator.fill: Test timeout of 45000ms exceeded.
  - waiting for locator('#wip-limit')
  - locator resolved to <input min="1" required="" type="number" id="wip-limit" .../>

Diagnosis: the expect.poll hardening from 12ce18c6 succeeded — Playwright shows the input resolved. The downstream .fill() call then failed its auto-wait actionability checks for ~45s. Likely cause: Vue template re-render (or the v-if + transition combo) detaches and re-attaches the DOM node during the fill's waiting window, so stability / pointer-events checks keep failing. Proving and fixing this requires template-level investigation that is out of scope for the PR.

Decision — fallback, not iterate: commit b8bb189b splits worker defaults:

• CI default = 1 (matches pre-TST-60 status quo; Smoke stays green)
• Local default = 2 (modest dev-box speedup inside the contention budget)
• TASKDECK_E2E_WORKERS env override still works both ways

What ships:

• fullyParallel: true enablement plumbing
• resolveWorkers helper + env var
• SQLite connection tuning (Pooling=True;Default Timeout=30)
• Hardened WIP-limit spec (defensive against the checkbox→v-if race)
• Local worker cap (was unbounded at Playwright default ~cores/2)

What does not ship: the "40% runtime reduction" acceptance criterion (#867). CI timing is unchanged because CI default is back at 1 worker.

Follow-up issue needed (not filed yet; flag this in the docs sweep):

"TST-60 follow-up: resolve Vue-re-render / Playwright actionability race on WIP-limit smoke so CI workers=2 default can ship. Evidence: locator resolved to <input> followed by 45s .fill() actionability timeout under 2-worker CI contention."

This turns #867 into an infrastructure-only PR that doesn't block merge while leaving the runtime-reduction work explicitly on the roadmap.

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[chatgpt-codex-connector]

Make WIP-limit retry idempotent

The retry loop clicks #column-has-wip-limit on every poll while #wip-limit is still absent, which can repeatedly toggle the checkbox on/off under UI lag and keep the input from ever appearing. In the exact high-contention scenario this change targets, a delayed render can cause alternating clicks to cancel each other and hit the 8s timeout, reintroducing flake in this smoke test. The retry should use an idempotent action (check() or isChecked() guard) before waiting for #wip-limit visibility.

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[Chris0Jeky]

Adversarial Code Review -- PR #949

Scope reviewed: frontend/taskdeck-web/playwright.config.ts (92 additions, 3 deletions), frontend/taskdeck-web/tests/e2e/smoke.spec.ts (21 additions, 2 deletions). Five commits examined: initial parallelization, WIP-limit hardening, local worker cap, Cache=Shared removal, CI/local worker split.

CI status: all 15 checks green including E2E Smoke.

---

P1 -- WIP-limit retry loop can toggle the checkbox indefinitely (smoke.spec.ts, lines ~301-311)

Validated from chatgpt-codex-connector finding. This is a real bug.

The expect.poll callback calls wipCheckbox.click() every iteration when wipLimit.count() === 0. Under CPU contention (which is the exact scenario this code was written for), the poll interval can fire faster than Vue's v-model propagation completes. This creates a sequence like:

1. Poll fires, checkbox is unchecked, #wip-limit count is 0 -> clicks checkbox (now checked)
2. Vue starts propagating, hasn't rendered #wip-limit yet
3. Poll fires again, #wip-limit count is still 0 -> clicks checkbox again (now UNchecked)
4. Vue finishes propagating from step 1, renders #wip-limit, then step 3's uncheck propagates and hides it again
5. Repeat until timeout

The test has an await expect(wipCheckbox).toBeChecked() assertion AFTER the poll loop, which would catch the final state. But the poll itself can spend 8 seconds toggling on/off before timing out, which is the exact flake this was supposed to fix.

Fix: Use an idempotent approach. Check the current state before clicking:

await expect
  .poll(
    async () => {
      if (await wipLimit.count() === 0 && !(await wipCheckbox.isChecked())) {
        await wipCheckbox.check()  // .check() is idempotent -- no-op if already checked
      }
      return await wipLimit.count()
    },
    { timeout: 8_000, message: 'Expected WIP limit input to render after toggling the checkbox' },
  )
  .toBeGreaterThan(0)

Using .check() instead of .click() is idempotent -- it only checks if unchecked. Combined with the isChecked() guard, this prevents the toggle-oscillation under contention.

---

P2 -- Default Timeout=30 does not control SQLite busy-wait behavior (playwright.config.ts, line ~28)

The comment says:

Default Timeout=30 -- wait up to 30 seconds on a busy lock before surfacing SQLITE_BUSY.

This is incorrect. In Microsoft.Data.Sqlite, the Default Timeout connection string parameter maps to SqliteCommand.CommandTimeout, which controls the command execution timeout (how long a .NET command object waits before canceling), not the SQLite-level PRAGMA busy_timeout. The command timeout is enforced by the ADO.NET layer via cancellation token, not by SQLite's internal busy handler.

To actually control SQLite's busy-wait (how long it retries when another connection holds a lock), you need either:

• PRAGMA busy_timeout = 30000; executed at connection open, or
• A busy_timeout parameter if the provider supports it (Microsoft.Data.Sqlite does not expose this as a connection string key)

EF Core + Microsoft.Data.Sqlite does not automatically set busy_timeout. The default is 0ms -- meaning any lock contention immediately returns SQLITE_BUSY with no retry.

Impact: Under parallel E2E, with CI defaulting to 1 worker this is currently benign. But the stated intent of the connection string tuning is to support parallel runs, and Default Timeout=30 does not achieve that goal. The comment is misleading for future contributors who may bump workers expecting busy-wait protection.

Fix: Either:

1. Set busy_timeout via a raw SQL pragma at startup (requires backend code change, out of scope), or
2. Correct the comment to acknowledge that Default Timeout is command-level, not busy-wait-level, and note that proper busy_timeout is a follow-up, or
3. If the backend's DbContext OnConfiguring or a connection interceptor could execute PRAGMA busy_timeout=30000, that would be the correct fix.

---

P2 -- PR description is stale and contradicts the shipped code (PR body)

The PR body says:

"CI workers default to 2 (was 1)"
"Tighten E2E SQLite connection string with Cache=Shared;Pooling=True;Default Timeout=30"

The shipped code:

• CI workers default to 1 (not 2)
• Cache=Shared was removed in commit 577eabd

This mismatch means anyone reading the PR description (including future contributors doing git log) gets incorrect information about what this PR actually ships. The description was written before the fixup commits and never updated.

Fix: Update the PR description to match reality: CI defaults to 1 worker, local defaults to 2, Cache=Shared is intentionally omitted.

---

P2 -- fullyParallel: true with CI workers=1 is a no-op that adds cognitive load

The PR sets fullyParallel: true but then defaults CI to 1 worker. With a single worker, fullyParallel has no observable effect -- tests run serially within the single worker regardless. The combination creates a misleading configuration: a reader sees "parallel enabled" but CI behavior is identical to the pre-PR state.

The commit message (b8bb189) acknowledges this is a fallback, and the env-var override makes it possible to opt in. The honesty is appreciated. However, the TST-60 acceptance criterion ("40%+ runtime reduction") is explicitly not met by this PR. The PR title says "enable Playwright parallelization" but what ships is "install parallelization plumbing, keep CI serial."

Recommendation: Not a code bug, but the PR title should reflect reality. Something like "test(e2e): add parallel E2E infrastructure (TST-60, #867)" would be more accurate. The issue (#867) should not be auto-closed by this PR if the acceptance criterion is unmet.

---

P3 -- resolveWorkers accepts "0" via regex but rejects it downstream (playwright.config.ts, lines ~398-416)

The regex /^\d+$/ matches "0", which then passes to Number.parseInt yielding 0, which is caught by parsed < 1. This works correctly but the validation flow is slightly misleading -- the regex comment says "positive integer" but the regex allows zero. The < 1 check saves it, so this is cosmetic, not a bug.

---

P3 -- No Playwright test.describe.configure for WIP-limit test

The WIP-limit test relies on sequential card additions to the same column (first card must exist before the second is rejected). With fullyParallel: true, if Playwright ever splits individual tests within the same file across workers, the shared board state could be corrupted. Currently this is safe because each test creates its own board via test.beforeEach, but the pattern of multiple addCard calls within a single test depending on order is worth flagging as a latent concern if tests are ever decomposed.

---

Bot Finding Validation

Bot	Finding	Verdict
gemini-code-assist	Cache=Shared discouraged	Valid, but already fixed in commit 577eabd. No action needed.
chatgpt-codex-connector (P2)	Unbounded local workers	Valid, but already fixed in commit cb6fb1c. Local now defaults to 2.
chatgpt-codex-connector (P1)	WIP-limit retry toggles repeatedly	Valid and still present in the shipped code. See P1 above.

---

Summary

The infrastructure plumbing (worker resolution, env-var override, connection string extraction) is well-structured and the defensive comments are appreciated. The honest caveats section in the PR description is good engineering culture. However:

• P1: The WIP-limit poll loop has a real toggle-oscillation bug under the exact contention scenario it targets. Should be fixed before merge.
• P2: The Default Timeout comment is factually wrong about what it controls in Microsoft.Data.Sqlite. Should be corrected.
• P2: PR description is stale (says Cache=Shared and CI=2 workers, code says neither).
• P2: Closing TST-60: Enable E2E test parallelization #867 when acceptance criterion is explicitly unmet is misleading.