fix(browse): sanitize lone Unicode surrogates at commandResult chokepoint + /batch envelope (#1440)

Page captures with mixed-script Unicode round-trip cleanly to the Claude API.
Two new utilities in browse/src/sanitize.ts: stripLoneSurrogates for raw UTF-16
strings, stripLoneSurrogateEscapes for \uXXXX JSON escape text. sanitizeBody
picks the right pass based on cr.json.

buildCommandResponse is extracted from handleCommand (now exported) and
applies sanitization before new Response(). /batch was bypassing this
chokepoint via direct JSON.stringify, so it sanitizes each cr.result before
pushing AND wraps the envelope with stripLoneSurrogateEscapes. Defense in
depth wraps at getCleanText, getCleanTextWithStripping, html, accessibility,
and snapshot.ts return points so downstream consumers (datamarking, envelope
wrapping) see sanitized text before the response is built.

25 new unit tests across sanitize.test.ts and build-command-response.test.ts.
content-security.test.ts updated to accept either pre- or post-sanitize form
of the snapshot scoped branch (source-level regression check).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

plan-design-review/SKILL.md

@@ -1587,6 +1587,78 @@ For design debt: missing a11y, unresolved responsive behavior, deferred empty st
 
 Then present options: **A)** Add to TODOS.md **B)** Skip — not valuable enough **C)** Build it now in this PR instead of deferring.
 
+## Implementation Tasks
+
+Before closing this review, synthesize the findings above into a flat list of
+build-actionable tasks. Each task derives from a specific finding — no padding.
+Emit the markdown section AND write a JSONL artifact that `/autoplan` can
+aggregate across phases.
+
+### Markdown section (always emit)
+
+```markdown
+## Implementation Tasks
+Synthesized from this review's findings. Each task derives from a specific
+finding above. Run with Claude Code or Codex; checkbox as you ship.
+
+- [ ] **T1 (P1, human: ~2h / CC: ~15min)** — <component> — <imperative title>
+  - Surfaced by: <section name> — <specific finding text or line reference>
+  - Files: <paths to touch>
+  - Verify: <test command or manual check>
+- [ ] **T2 (P2, human: ~30min / CC: ~5min)** — ...
+```
+
+Rules:
+- P1 blocks ship; P2 should land same branch; P3 is a follow-up TODO.
+- If a finding produced no actionable task, do not invent one.
+- If a section had zero findings, emit `_No new tasks from <section>._`
+- Effort uses the AI-compression table from CLAUDE.md.
+
+### JSONL artifact (always write, even if zero tasks)
+
+`/autoplan` reads this file to aggregate across phases. Build each line with
+`jq -nc` so titles and source findings containing quotes, newlines, or
+backslashes serialize cleanly — never use hand-rolled `echo` / `printf`.
+
+```bash
+eval "$(~/.claude/skills/gstack/bin/gstack-slug 2>/dev/null)"
+TASKS_DIR="${HOME}/.gstack/projects/${SLUG:-unknown}"
+mkdir -p "$TASKS_DIR"
+TASKS_FILE="$TASKS_DIR/tasks-design-review-$(date +%Y%m%d-%H%M%S).jsonl"
+COMMIT=$(git rev-parse HEAD 2>/dev/null || echo unknown)
+BRANCH=$(git branch --show-current 2>/dev/null || echo unknown)
+RUN_ID="$(date -u +%Y%m%dT%H%M%SZ)-$$"
+
+# Repeat ONE jq invocation per task identified during this review.
+# Substitute the placeholders inline with shell variables you set per task:
+#   TASK_ID (T1, T2, ...), PRIORITY (P1/P2/P3), COMPONENT, TITLE,
+#   SOURCE_FINDING, EFFORT_HUMAN, EFFORT_CC, FILES_JSON (a JSON array literal
+#   like '["browse/src/sanitize.ts","browse/src/server.ts"]').
+jq -nc \
+  --arg phase 'design-review' \
+  --arg run_id "$RUN_ID" \
+  --arg branch "$BRANCH" \
+  --arg commit "$COMMIT" \
+  --arg id "$TASK_ID" \
+  --arg priority "$PRIORITY" \
+  --arg component "$COMPONENT" \
+  --arg effort_human "$EFFORT_HUMAN" \
+  --arg effort_cc "$EFFORT_CC" \
+  --arg title "$TITLE" \
+  --arg source_finding "$SOURCE_FINDING" \
+  --argjson files "$FILES_JSON" \
+  '{phase:$phase, run_id:$run_id, branch:$branch, commit:$commit, id:$id, priority:$priority, component:$component, files:$files, effort_human:$effort_human, effort_cc:$effort_cc, title:$title, source_finding:$source_finding}' \
+  >> "$TASKS_FILE"
+```
+
+If `jq` is not installed, fall back to skipping the JSONL write and warn
+the user to install jq for autoplan aggregation. Never hand-roll JSONL.
+
+If zero tasks were identified in this review, still touch the JSONL file
+(`: > "$TASKS_FILE"`) so the aggregator sees that the phase produced output
+this run (an empty file means "ran, no findings" — distinct from "didn't run").
+
+
 ### Completion Summary
 ```
   +====================================================================+

plan-design-review/SKILL.md.tmpl

@@ -372,6 +372,8 @@ For design debt: missing a11y, unresolved responsive behavior, deferred empty st
 
 Then present options: **A)** Add to TODOS.md **B)** Skip — not valuable enough **C)** Build it now in this PR instead of deferring.
 
+{{TASKS_SECTION_EMIT:design-review}}
+
 ### Completion Summary
 ```
   +====================================================================+