fix(compression): show a retry when settings fail to load

[woodsonl]

Summary

• When GET /api/settings/compression fails (a 5xx, or a network error during a server restart), CompressionPanel (/dashboard/context/settings) and CompressionSettingsTab (embedded in /dashboard/context/caveman) now show "Prompt Compression: Failed To Load" and a Retry button in place of their controls. Retry shows the loading state, re-runs the component's loads, and the controls come back once a GET succeeds. Both load effects return a cleanup, so answers that arrive for a run a retry replaced are ignored.
• Before this change, .catch(() => {}) swallowed the failure and .finally(() => setLoading(false)) rendered the editable controls on DEFAULT_CONFIG (engines: {}, outputStyles: [], the default contextBudget), and lastConfirmedRef kept those defaults. The output-style toggles and the context-budget dial are live at once, so the next click overwrote the stored outputStyles or contextBudget with the defaults plus one change. Turning on the master switch (shown off) unlocked the engine toggles. One engine toggle then PUT a one-entry engines map, which sanitizeEnginesForWrite (src/lib/db/compression.ts) stored with enginesExplicit: true, so dispatch followed that one-entry map. The tab's defaults have compression off, so it hid its editable sections and reported every layer as off.
• The derived-pipeline text moves into a derivedPreviewText helper. That keeps CompressionPanel at the complexity cap of 15 that the if (loadFailed) return would otherwise exceed.
• The message reuses settings.compressionTitle, common.failedToLoad and settings.retry, which all 67 locales already carry, so no catalog changes are needed. Its text uses text-red-600 dark:text-red-400, the repo's most common error-text pair. Computed from Tailwind's OKLCH values against the card surface, that is 4.8:1 in the light theme (#ffffff) and 6.0:1 in the dark theme (#161b22), above the WCAG AA minimum of 4.5:1. The previous text-red-500 measures 3.8:1 in the light theme.
• CompressionSettingsTab already imported Button without using it. The retry button now uses it, so the tab's frozen @typescript-eslint/no-unused-vars entry comes out of config/quality/eslint-suppressions.json (lint-staged fails on an unused suppression).

Related Issues

• No issue filed. Coordinates with the open branches fix/compression-panel-partial-save and fix/compression-engines-partial-write (see Reviewer Notes).

Validation

• Change type: UI
• Red first: commit 615f5f5 adds the first tests alone. On it the 3 new cases fail and the 11 existing cases in those files pass. With the settings GET answering 500, the switch sweep records 18 settings PUTs: { enabled: true }, engines maps that start one-entry ({ "session-dedup": { enabled: true } }), one-entry outputStyles lists, and liveZone. Commit 2104355 adds the stale-load cases. On it they fail (the panel's MCP toggle and the tab's rule list take the superseded load's values), and the 17 other cases pass.
• Green: npx vitest run --config vitest.config.ts on the 9 files that render either component passes 50/50, including the caveman page that embeds the tab.
• Mutation check: six mutants, each caught by exactly its intended test. In each component, they are: Retry clearing the error without showing loading, the thrown-fetch catch swallowing the error, and the effect without its cleanup.
• npm run lint: ESLint on the 4 changed source and test files (--suppressions-location config/quality/eslint-suppressions.json --pass-on-unpruned-suppressions) is clean. The full lint runs in the CI lint job.
• node scripts/check/check-complexity-ratchets.mjs --base-ref 4db3c54ec1: OK, 3 violations in the touched files against 3 at the base. npm run check:dashboard-typecheck: OK, within the frozen baseline. npx prettier --check on the changed files is clean.
• Reconciled with the active release base: cut from release/v3.8.52 at 228d72d. git merge-tree against the current tip is clean, and none of the files changed here moved on the base.
• Production-code changes include new automated tests in this PR.

Tests Added Or Updated

• tests/unit/ui/compressionPanel.test.tsx, new describe("CompressionPanel when the settings GET fails"):
  • After a 500 and after a thrown fetch, pressing every switch the panel offers sends no settings PUT, no select or input renders, and a Retry is offered.
  • Retry with the retried GET held open shows loading and no controls. Once the GET answers, the stored rtk level loads, and the master switch saves { enabled: false }.
  • When the first load's mcp-accessibility GET answers after a retry finished, the toggle keeps the retried value.
• tests/unit/ui/compression-settings-tab-partial-save.test.tsx, new describe("CompressionSettingsTab when the settings GET fails"):
  • After a 500 and after a thrown fetch, the tab shows the error and Retry in place of the all-off default summary.
  • Retry with the retried GET held open shows loading and no form, then the stored, enabled settings.
  • When the first load's rules GET answers after a retry finished, its rules stay out of the list.

Coverage Notes

• The new cases cover every path added in both components: the 500 and thrown-fetch failures, the error card, Retry and its loading window, and the stale-answer cleanup.
• These are .tsx vitest UI tests. ci.yml's test-vitest job runs them on this PR (npm run test:vitest:ui). In the CI run on 06fe786, both files ran and passed: compressionPanel.test.tsx (8 tests) and compression-settings-tab-partial-save.test.tsx (12 tests).

Reviewer Notes

• ⚠️ base-red inherited: 🔴 Release branch not green: release/v3.8.52 #15306
• CI failures on this PR that come from the base or the runner:
  • Fast Quality Gates, gate cycles: every PR against release/v3.8.52 fails it the same way (for example fix(executors): route GHE Copilot GPT-6 models to Responses #15499 and fix(providers): load the ChatGPT web validator only when it is tested #15516), with the same 14 strongly connected components. After fix(ci): make check-cycles honest — real graph walk + cycles ratchet (#15159 G-01/G-02) #15281, ci.yml runs check:cycles:ratchet, but quality.yml still runs the plain check:cycles, which exits 1 on any cycle. 🔴 Release branch not green: release/v3.8.52 #15306 does not list it.
  • Fast Quality Gates, gate complexity-ratchets (second run): it reports FeatureFlagCard.tsx: 1 → 2, a file this PR does not touch. The gate measures new code from github.event.pull_request.base.sha, which is still this PR's opening base, 4db3c54. The job merges into the current tip, 23a1148, so the gate sweeps in the three base commits that landed after this PR opened, including feat(dashboard): add description display modes to feature-flags cards #12740, whose own run printed the same line. Against 23a1148, this PR's files read 1 → 1 (CompressionPanel.tsx) and 2 → 2 (CompressionSettingsTab.tsx).
  • Integration Tests (2/2) (second run): batch-e2e-rate-limit.test.ts failed before serving a request, because its dev server hit listen EADDRINUSE on the free port the test had picked. The test releases that port, and the server binds it 15 to 18 seconds later. This PR touches no server code, integration test or dev script.
  • Build: fork PRs build on the hosted ubuntu-latest runner, which is shut down partway through the Next build ("The runner has received a shutdown signal"). Other fork PRs fail the same way (for example fix(combo): type the custom-model row in the auto pool check #15461, fix(cli): scope the serve port guard to the bind address #15472 and fix(sse): drop a replayed responses event when the sequence is a string #15510), while base pushes build on the self-hosted runner.
  • Vitest (MCP / autoCombo / UI components): every test passes. The UI step exits 1 on unhandled ReferenceError: window is not defined errors raised after teardown by other files (comboLiveStudio.test.tsx, flowCanvas.test.tsx, providerCardAudioBadge.test.tsx). The base push on 23a1148 fails the same way.
  • Lint: npm run audit:deps stops on the critical advisory for next 16.2.0 - 16.3.5 (GHSA-vcvr-r3jv-pc5j) before ESLint runs. Base pushes fail the same step.
  • Docs Sync (Strict): translation drift on docs/architecture/QUALITY_GATES.md at the base.
  • Merge integrity: check:agent-skills-sync finds skills/omni-providers stale against docs/openapi.yaml at the base. check:changelog-integrity passes.
  • Gate / CI and Gate / Quality summarize the jobs above.
• The complexity-ratchet failure from the first CI run came from this PR and is fixed in 06fe786.
• Coordination: fix/compression-panel-partial-save rewrites save() and the refs above it, and fix/compression-engines-partial-write merges engines by id and changes setEngine. Both also edit CompressionPanel.tsx and compressionPanel.test.tsx. This PR leaves save(), those refs, setEngine and setupFetchMock untouched, and adds its tests in a separate describe. git merge-tree against the current heads (e3529ed and 42c7027) reports no conflicts. On each trial merge, the compression UI suites pass: 58/58 with the partial-save branch and 53/53 with the engines branch, including its compressionPanelEnginesPartialWrite.test.tsx.
• The panel's Retry re-runs all three loads (settings, mcp-accessibility, combos), since a server restart fails them together.

Browser QA

A real-Chromium pass against a local dev server serving 06fe786, with GET /api/settings/compression patched to answer 500:

• With an unpatched load first, the panel renders its controls. After arming the patch and remounting the panel through client-side navigation, the panel is replaced by a role="alert" card reading "Prompt Compression: Failed To Load" with exactly one Retry button.
• The card text renders in the darker red on the light theme and the lighter red on the dark one; screenshots of both themes confirm the text is legible on the card.
• Clearing the patch and pressing Retry re-runs the loads and restores the full control panel; the alert is gone.
• The Caveman page, which does not read this endpoint, rendered normally during the pass.