Ship keepstyle guideline split and dedupe worker report envelopes

[TheGreatAxios]

Summary

• Splits the chat Guidelines block into five named sub-blocks (GUIDELINE_SUB_BLOCK_IDS) with an id-based omit policy, so config profiles can ship a smaller keepstyle footprint via promptSectionOmit without prose surgery.
• Ships KEEPSTYLE_PROMPT_SECTION_OMIT: responseStyle and scope/conventions (build gate, verification evidence) stay; toolChoice, askVsProceed, and orchestration drop. Omitting the config keeps full guidelines, so the default prompt is unchanged.
• Dedupes worker report envelopes: intern, testsmith, neckbeard, and bruckheimer packages stop re-specifying the four-heading envelope and point at the shared scaffold that owns its shape. Skywalker keeps the orchestrator-side contract (no Skywalker policy change).
• Contract markers are substring-stable: no behavior change to marker matching.

Why: keepstyle models pay prompt tokens for guidance they never act on, and envelope re-specs drift into competing taxonomies; one policy surface and one envelope owner fix both.

Verification

• bun test src/agent/prompts.test.ts src/agent/directors/intern/package.test.ts src/agent/directors/testsmith/package.test.ts src/agent/directors/neckbeard/package.test.ts src/agent/directors/bruckheimer/package.test.ts src/agent/directors/draper/package.test.ts — 88 pass, 0 fail (exit 0)
• bun run check — green: lint + typecheck + build + guard, then 7137 pass, 0 fail across 488 files (exit 0)
• Contract tests assert all five guideline markers present by default, the keepstyle omit keeps response-style/scope while dropping the three blocks, unknown omit ids are ignored, guidelineConfig threads through buildChatSystemPrompt, and the four-heading envelope appears exactly once in built sub-agent prompts; director tests assert packages no longer re-specify ## Findings / ## Blockers / ## Paths
• Live-eval plan (unspent — no live model calls made from this branch; second-to-land rebases onto CL-7665 if it lands first, since it edits nearby guideline scope):
• bun scripts/eval-capability.ts --matrix <cells> --dry-run — lists cases x variants with zero spend; drop --dry-run to run post-rebase with configured credentials
• Gates on the live run: report envelope present in worker outputs per provider family, grok cell within its ≤17 gate, kimi cell (kimi-k2.7-code) included

Fixes CL-7654

[linear-code]

CL-7654

[TheGreatAxios]

Audit: envelope direction is correct — scaffold owns the Summary/Findings/Blockers/Paths shape, lane packages point at it instead of re-specifying it. Endorsed.

Two issues to fix before merge:

1. omit is untyped at the boundary. GuidelineConfig.omit and the buildGuidelines opts field are readonly string[], and ProfileSchema accepts "promptSectionOmit?": "string[]" — with "Unknown ids are ignored" as the documented behavior. Per the repo arktype-at-boundaries rule, constrain omit to the GuidelineSubBlockId union and validate promptSectionOmit against GUIDELINE_SUB_BLOCK_IDS at profile load (type.enumerated(...) matches the existing settings.ts pattern) instead of silently ignoring unknown strings. A typo in a profile today vanishes without a trace.
2. KEEPSTYLE_PROMPT_SECTION_OMIT is a dead export: nothing outside prompts.test.ts references it — no keepstyle profile or call site is wired to it. Either wire a keepstyle profile to it or drop the export (and its tests) rather than shipping plumbing with no consumer.

Note: this PR wins the envelope question vs #954 — #954 must yield its in-package report format to this scaffold-owned shape.