test(app): isolate component coverage with storybook - #45142

Summary

• Add package-owned Playwright component suites: 44 Session UI tests and 1 app Composer test.
• Keep exactly five net-new Storybook entries: Conversation, AgentResearch, ChangingFiles, TerminalCommands, and InteractiveComments. Existing entries remain; variants use serializable args/globals and interactive controls.
• Share test-only configuration and mounting in packages/storybook/playwright/. Component suites remain separately filterable from default unit/browser tests and required full-app E2E CI.
• Preserve original source-path provenance comments and all new upstream tests.

Assertion Restoration

A case-by-case audit found that some earlier moves preserved visible outcomes but lost fixture or integration guarantees. This revision restores all 19 weakened cases without new Storybook entries:

• Restore 30 complementary E2E cases, including the five live transport tests, production compaction/retry/lifecycle events, active collapsed edits, real app scrolling, empty-draft/single-variant Composer configuration, persisted locales, reasoning matrices, model catalog hydration, and whole-app owner warnings.
• Keep useful isolated component and client-parser coverage alongside the restored integrations; local fixture state is not treated as proof of reducer or transport behavior.
• Restore the exact modified/added/deleted three-file patch and deletion re-collapse sequence, real dismissed-question visibility, singleton read metadata, TypeScript write fixture, and URI attachment source.
• Add a separate shell input-completion phase before execution, multiline output growth and independent sibling controls. Preserve busy/message-completion separation.
• Strengthen app no-scroll coverage with actual overflow, a visible focused command away from the bottom, and the real app scroll owner.
• Observe compaction partial summaries before failure/cancellation, then assert their removal through real event handling.

The independent re-audit covers all 132 expanded merged-v2 baseline contracts, cross-checked against the initial 124-case baseline. Final coverage is 113 full-app E2E contracts + 19 intentionally isolated rendering contracts. The full component suite remains 45 tests, including supplemental coverage. The earlier 19 assertion gaps were restored; the separately approved animation-sampling policy change below intentionally removes two animation-only assertions. Rendering and integration checks still have different execution boundaries.

Focused Animation Policy

At Brendan's request, remove only the flaky expectTerminalTopMotion requirement in terminal-hidden.spec.ts: more than six sampled positions and a maximum per-sample movement below 30% of the range. Remove its unused sample/reset helper code. 0 test cases removed; 1 mixed test retained; 2 animation-only assertion sites removed. All other 53 assertion sites in that file, including final geometry, alignment, visibility, caching and placement behavior, are unchanged. Other animation-event and performance-profiling checks were not swept. This is an intentional coverage-policy change, not a claim of identical animation coverage.

The focused terminal test passed 10 repetitions with 5 workers, including the parallel workload that previously reproduced the sampling failure.

Validation

• packages/session-ui: systemd-run --user --scope --quiet -p TasksMax=768 bun run test:components -- --workers=2 — 44 passed.
• packages/app: same component command — 1 passed.
• packages/app: PATH=/tmp/opencode/node-bun:$PATH systemd-run --user --scope --quiet -p TasksMax=768 --setenv=PATH=/tmp/opencode/node-bun:$PATH bun run test:e2e -- --workers=5 — 113 passed.
• App unit/browser suites — 540 + 45 passed.
• Session UI unit suite — 112 passed.
• Client unit suite — 83 passed, including supplemental parser checks.
• App, app-E2E, Session UI and client typechecks — passed.
• Storybook production build — passed.
• Prettier and git diff --check — passed.
• Merge-base export audit — exactly 5 net-new Storybook entries.

Requested by: @Brendonovich (Brendan via Slack)