Remove AGENTS.md Section 21 (Workflow Skills) via Frontmatter Parity

Context

PR #11421 and #11424 (Phase B description-router hardening) and compaction efforts have successfully populated the description frontmatter for all Anthropic-style Progressive Disclosure skill routers (.agents/skills/**/SKILL.md). These descriptions are parsed and natively injected into the turn-based memory environment (as seen in the "Available skills:" section of the system prompt).

The Problem

AGENTS.md currently contains ## 21. Workflow Skills (when to invoke), a large markdown table that duplicates these triggers.

1. Token Budget Drain: This table consumes significant byte-budget against the strict 24KB Context Window Truncation limit.
2. Substrate Philosophy Violation: By packing high-density execution rules (e.g., merge-gate restatements, Evidence Audit rules) into the table's "Trigger condition" column, we are violating ADR 0007's "Map vs. World Atlas" discipline. The AGENTS.md file should be a low-density routing Map, not a high-density cheat sheet. Agents must read the actual SKILL.md payload (the Atlas) for execution instructions.

The Architectural Reality

A deep Verify-Before-Assert (V-B-A) analysis confirms that the skill router frontmatter descriptions are already at parity or stronger than the AGENTS.md table for almost every skill. The only identified gaps are:

• ideation-sandbox: Frontmatter is missing the auto-fire trigger for "§5.2 Step 2.5 Architectural Step-Back on high-blast-radius proposals before [RESOLVED_TO_AC] / [GRADUATED_TO_TICKET] graduation".
• tech-debt-radar: Frontmatter is missing the explicit trigger "During PR review for fundamental architectural shifts". (Note: pr-review lacks the highly-compressed rule cheat-sheet in its frontmatter, but removing it enforces the intended discipline of making the agent read the SKILL.md instead of relying on a summarized cheat-sheet).

The Fix

1. Patch the frontmatter descriptions for ideation-sandbox and tech-debt-radar to include their missing edge-case triggers.
2. Fully delete ## 21. Workflow Skills (when to invoke) from AGENTS.md.
3. Update ADR 0007 (Compaction Taxonomy) to document this final phase of the Map vs. Atlas compaction victory.

Contract Ledger Matrix

Acceptance Criteria

• ideation-sandbox/SKILL.md frontmatter updated to include Step 2.5 Architectural Step-Back trigger.
• tech-debt-radar/SKILL.md frontmatter updated to include the PR review hook trigger.
• AGENTS.md ## 21. Workflow Skills is deleted.
• learn/agentos/decisions/0007-agents-md-compaction-taxonomy.md (or equivalent ADR) updated to reflect the removal of the skills table from the Map.

Out of Scope

• Altering the behavior or execution logic of any skills.
• Changing the turn-memory-pre-flight mechanism.

Avoided Traps

• Trap: Keeping the table as a "cheat sheet". Rejected because it violates ADR 0007 (Map vs Atlas) and consumes critical 24KB headroom. If an agent needs the rules, they must view_file the SKILL.md.

Related

• ADR 0007

Origin Session ID: d1aee218-8c42-4562-b2ec-f597284fa9d7 Handoff Retrieval Hint: "AGENTS.md section 21 workflow skills frontmatter compaction"