docs/test-plan.md — the one-shot ledger

Holding pen for manual verifications that haven't been codified as
committed tests yet. See DESIGN.md §17.2 for the discipline.

Every entry has the same shape:

## <short title>

- **What was verified**: …
- **How it was verified**: …
- **What test should replace this note**: …
- **Tracked**: <commit / PR / issue link>

Empty is good. A long list here is a code-smell signal that some test
needs writing.

Schema-load smoke (already codified — keep as the template)

• What was verified: that schema/coderef.schema.json parses as
  valid JSON and that examples/minimal.coderef.jsonc validates
  cleanly against it.
• How it was verified: ran python3 tools/validate-config.py schema/coderef.schema.json examples/minimal.coderef.jsonc locally
  during the schema PR (commit c7c4fe9).
• Replaced by: .github/workflows/ci.yml job schema — runs the
  same validation on every push.
• Tracked: commits c7c4fe9, cfc9263.

This entry is kept as documentation of the template. New entries go
below.

VSCode extension end-to-end (closed — codified)

• What was verified: extension activates in a workspace
  containing .coderef.jsonc; DocumentLinks resolve for planted
  TODO(@user) markers; hover returns content with pattern id +
  description; coderef.explainReference is registered.
• Replaced by: extension/src/test/runtime/extension.test.ts,
  run via @vscode/test-electron (script: npm run test-runtime).
  CI runs the same path in the VSCode extension (TS + VSIX) job.
• Tracked: closed by the PR adding @vscode/test-electron.

UTF-16 vs UTF-8 offset mismatch in providers.ts (closed — codified)

• What was verified: hover, document-link, and the
  coderef.explainReference command translate between VSCode's
  UTF-16 positions and the engine's UTF-8 byte_start / byte_end
  rather than comparing them naively. Previously they used
  document.offsetAt() (UTF-16) against engine byte offsets
  (UTF-8); a single em-dash earlier in the file misaligned all
  subsequent lookups.
• Replaced by: extension/src/textOffset.ts (helper) +
  extension/src/textOffset.test.ts (unit tests covering em-dash,
  emoji surrogate pairs, CJK round-trip, off-by-one boundary cases)
  • a new runtime test
    extension/src/test/runtime/extension.test.ts:hover-resolves-the-SECOND-TODO-bob
    that hovers TODO(@bob) after an em-dash + emoji in the fixture.
    Any regression to UTF-16-vs-UTF-8 comparison fails the hover
    lookup in that test.
• Tracked: closed by the PR adding extension/src/textOffset.ts.