refactor(mobile): remove obsolete whole-file review highlighters

[juliusmarminge]

The whole-file review highlighting APIs had no production callers. Their result caches and rendering helpers survived only behind that unused path.

Remove both APIs and their exclusively owned code. Move the existing row-preservation and long-line regressions to highlightSourceFile, and paired word-diff emphasis to highlightReviewSelectedLines. Live source, snippet, selected-line, engine initialization and language caching algorithms are unchanged.

Verification: 29 focused highlighter, source-cache, word-diff and native-engine tests passed before and after. All five Shiki cases remain. Mobile typecheck, targeted lint/format, and diff checks passed. No visual change.

Model: gpt-6 astra. Harness: Codex in T3 Code.

Note

Remove obsolete whole-file review highlighters from shikiReviewHighlighter

• Removes highlightReviewFile, streamHighlightReviewFile, and all supporting code for complete-file highlighting (caching, language resolution, chunked processing, word-diff application)
• Migrates existing tests to the highlightSourceFile and highlightReviewSelectedLines APIs, preserving coverage for source-line preservation, long-line fallback, initialization, word-diff, and snippet aliasing
• Drops the environment flag and utilities that controlled the file-result cache
• Behavioral Change: getHighlighter initialization diagnostics no longer report the file-result-cache setting; any external code referencing the removed exports or the cache disable flag will need to migrate to the source-file / selected-lines APIs

^{Macroscope summarized 2e2c114.}

[macroscopeapp]

Approvability

Verdict: Approved at 2e2c114

Macroscope's review found this PR approvable — This is a focused mobile dead-code cleanup removing unreferenced whole-file review highlighting, streaming, and cache machinery. Source, snippet, and selected-line highlighting remain in place, and the accompanying test changes cover those retained paths.

^{You can add or adjust custom eligibility rules. Learn more.}

[github-actions]

Thread transfer impact

✅ Thread transfer remains within every enforced ceiling.

ℹ️ The exact PR base did not have a successful artifact. Baseline uses the latest successful main measurement shown below.

Provider	Metric	Main baseline	This PR	Impact	PR ceiling
Codex	Total thread wire	13.5 KiB	13.5 KiB	+9 B (+0.1%)	15.1 KiB	✅
Codex	Thread snapshot wire	7.0 KiB	7.0 KiB	−4 B (−0.1%)	7.3 KiB	✅
Codex	Live turn WebSocket wire	6.5 KiB	6.5 KiB	+13 B (+0.2%)	7.8 KiB	✅
Codex	Live turn WebSocket decoded	57.0 KiB	57.0 KiB	0 B (0.0%)	66.4 KiB	✅
Codex	Live turn messages	8	8	0 (0.0%)	21	✅
Claude	Total thread wire	13.6 KiB	13.6 KiB	−24 B (−0.2%)	15.1 KiB	✅
Claude	Thread snapshot wire	7.0 KiB	7.0 KiB	−4 B (−0.1%)	7.3 KiB	✅
Claude	Live turn WebSocket wire	6.6 KiB	6.5 KiB	−20 B (−0.3%)	7.8 KiB	✅
Claude	Live turn WebSocket decoded	57.9 KiB	57.8 KiB	−44 B (−0.1%)	66.4 KiB	✅
Claude	Live turn messages	10	9	−1 (−10.0%)	21	✅

Baseline: 4631000 · PR result: 2e2c114 · Source CI: success

Scenario and decoded snapshot size

10 historical turns, 5 command tools per turn, 878.9 KiB retained MCP result per historical turn, and a 1.05 MiB retained result in the measured turn.

• Codex decoded thread snapshot: 113.8 KiB
• Claude decoded thread snapshot: 114.5 KiB

Updated in place by a trusted workflow. PR artifacts are strictly validated and never executed.