test(toolpath-desktop): vitest + unit tests for classify and flattenChatHead

[eliothedeman]

Summary

• Wires up Vitest as the frontend unit-test runner (Node environment, bun run test / bun run test:watch). No jsdom — the two modules under test are pure TS.
• Adds 5 tests for classify.ts covering the user / assistant / tool / system cases plus readStructural's preference for conversation-type payloads when multiple artifacts are present.
• Adds 5 tests for flattenChatHead in tree.ts covering the linear HEAD chain, tool.invoke sibling attachment, non-tool-sibling filter, bare Step doc fallback, and detached-HEAD fallback.

Closes #40.

Test plan

• bun run test — 10 / 10 passing.
• bun run check — svelte-check stays green (pre-existing a11y warnings only).
• bun run build — Vite production build succeeds.

[github-actions]

🔍 Preview deployed: https://5810d552.toolpath.pages.dev

[eliothedeman]

Summary

Covers all 10 tests named in #40 with minimal, readable fixtures. Tooling is cleanly wired, CI is green, no scope creep.

Notes

• classify.test.ts:17-42 — all 4 classify cases (user/assistant/tool/system) present; fixtures use the correct flat wire shape ({ type, role, text }), which is exactly the shape the original bug misread.
• classify.test.ts:45-62 — the readStructural multi-artifact test genuinely constructs a 2-artifact change map (file:///tmp/out.txt + tool://Edit) and asserts the tool payload wins. This is the regression the issue describes.
• tree.test.ts:50-64 — linear chain test checks both id order and kind sequence, catching either ordering or classification regressions.
• tree.test.ts:66-81 — tool.invoke sibling attachment test verifies s2.toolInvocations[0].id === "s3" AND that s3 is absent from the top-level list, which catches both prior bugs (missed splice, lost attachment).
• tree.test.ts:83-94 — non-tool sibling filter correctly uses a user sibling and asserts toolInvocations === [].
• tree.test.ts:96-115 — bare Step doc fallback and detached-HEAD fallback both present; the latter uses a literal "missing" head id, exactly the detached case.
• vitest.config.ts:7 — environment: "node" with no jsdom (jsdom is only a transitive optional peer, not an install dep). Matches the issue's "pure TS" note.
• package.json — adds test and test:watch scripts; only new devDep is vitest.
• bun.lock — additions are vitest's own transitive deps (@vitest/*, chai, tinybench, etc.); no unrelated churn.
• No Svelte component tests, no extra helpers beyond the three local fixture builders. Scope is tight.
• gh pr checks 45 — both test and deploy pass.

Verdict

Comment (would approve, but can't self-approve). Tests map 1:1 to the issue, fixtures exercise the actual regressions (not just the happy paths), and the tooling additions are minimal. Safe to merge.