feat(lab): gen-3 triage-workflow treatment folds all measured failure modes; v5_echo enforcement contrast

T1 (coding_markdown_v5 gen-3): one unified CORPUS WORKFLOW block replaces
the budget block + conditional routing line. Each bullet traces to a
measured failure: survey-first unconditional corpus grep (acq + antitrust
+ both pilots ran ZERO greps); cover-everything triage floor (acq left
12/31 docs wholly unexamined with ~70k headroom unused and the missed
criteria's evidence absent from every tool result); full-read-central
past truncation (Pinnacle negative pledge windowed past); note
corpus-gaps (C-058/59 absence misses); verify-at-source (Meridian
90-vs-60-day second-hand assertion error); interactions presented
together (C-027/C-032); anti-anxiety close damps the skip response
without promising compaction (deepseek lane has no compaction valve -
providerForModel(deepseek-*) never arms MIKE_OPENAI_COMPACT_THRESHOLD).

T2 (coding_markdown_v5_echo): identical serving + MIKE_EXPOSURE_ECHO=1 -
the one-shot exposure-accounted unexamined-list echo at generate_docx.
Philosophy contrast (harness measurement vs prompt suggestion) under the
max-3-significantly-different-treatments allowance (2026-08-06).

Freeze: v4-and-below serving untouched (appends only in the surface
file; ternary gated behind MIKE_TRIAGE_WORKFLOW which no frozen arm
sets). Preflight: v5/v5_echo prompt sha 6542264f, tool sha c8859b8e
(tools unchanged); tsc clean. Receipts: triage-workflow-prompt-v1 +
exposure-echo-v1 delta tags; grep-routing tag retired with gen-2.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011pfUVhNFTRvhYGXBwoKNj6