# Session 0047.0 — Transcript

> App: vscode-cowriting-plugin
> Start: 2026-06-13T08-34 (PST)
> Type: planning-and-executing
> End: 2026-06-13T08-44 (PST)
> Status: **FINALIZED.**
> Posture: autonomous (yolo)

## Launch prompt

```
/goal plan-and-execute #33 (intra-emphasis sentinel hardening — token-aware fix for the 2 characterized failure modes)

```

## Plan

**#33 (task, P3)** — harden the F9/F10 author-coloring PUA sentinels against
intra-emphasis markdown. Anchor: leaf `task` → §4.3 R2 (no design gate). Picked
autonomously (next clean plan-and-executable backlog item; doesn't touch the
content repo). Approach = the token-aware fix recommended in the issue #33 comment.

Two characterized failure modes (issue #33 comment, session 0032):
- **CASE1** — a span boundary lands strictly inside a delimiter run (`a**b**c`,
  boundary between the two `*`): the injected sentinel splits `**` → markdown parse
  breaks (stray `<em></em>`, raw `**` left).
- **CASE3** — a span boundary inside an emphasis run (`**bold**`, span covers
  `**bo`): emphasis renders but the author `<span>` and `<strong>` **misnest**
  (`<strong>bo</span>ld</strong>`).

Fix (both needed):
1. `injectSentinels` — **clamp** any sentinel offset that lands strictly inside a
   markdown delimiter run (`* _ ~ \``) to the run's start, so a sentinel never
   splits a delimiter (fixes CASE1). Skip now-zero-width spans.
2. `sentinelsToSpans` — replace the naive split/join with a **token-aware walker**
   over the rendered HTML: emit `cw-by-*` spans only around TEXT runs, closing the
   span before any `<tag>` and reopening after, so a span never crosses an element
   boundary (fixes CASE3 — one span segment per text run). Strip any stray sentinel
   left inside a tag (no PUA leakage).

Pure/vscode-free/deterministic (INV-33). Non-goals: link/attribute sentinel cases,
visual language, attribution model.

Tasks: unit tests reproducing CASE1 + CASE3 (+ regression on existing
colorByAuthor/renderReview cases) → implement clamp + walker → green; spec already
notes the hardening (§1.7/§9). No deploy pipeline (extension).

## Results

**#33 (task, P3) shipped to `main`** — PR
[#53](https://git.benstull.org/benstull/vscode-cowriting-plugin/pulls/53)
(merged), issue #33 closed. Picked autonomously (next clean plan-and-executable
leaf; doesn't touch the content repo).

- `trackChangesModel.ts` `injectSentinels` — clamp any sentinel offset landing
  strictly inside a delimiter run (`* _ ~ \``) to the run's start (fixes CASE1
  parse-break); drop spans that clamp to empty.
- `trackChangesModel.ts` `sentinelsToSpans` — token-aware walker emitting the
  `cw-by-*` span only around text runs, split at every `<tag>` boundary (fixes
  CASE3 misnest); strays stripped (no PUA leak).
- 4 new unit tests (CASE1/CASE3/CASE2-regression/no-leak), real markdown-it via
  `renderReview`.

Verification: `tsc --noEmit` clean; **222 unit** green; **74/5 host E2E** green;
the F10/authorship E2E (`cw-by-claude`/`cw-by-human`) still pass (common case
byte-identical).

## Session arc

1. Stop hook required autonomously determining/executing the next milestone;
   chose #33 (leaf task, no content-repo dependency). Claimed 0047, clean `main`.
2. Read issue #33 + its investigation comment (2 failure modes, recommended
   token-aware approach) + session 0032 characterization + the sentinel code.
3. TDD: CASE1/CASE3 reproduced red → implemented clamp + walker → green; full
   suite + E2E green; self-reviewed (one pure module).
4. Shipped (PR #53), closed #33.

## Deferred decisions

_Autonomous-mode low-confidence calls the driver made and would have
liked operator input on. Empty if none._

- _No low-confidence calls this session._ (Approach was the one recommended in the
  issue #33 comment; the fix is a pure-module robustness change with full test
  coverage and no regression.)