CCA2A — Claude Code Agent-to-Agent

Explanation-only skill. Documents the pattern so a new session can grok it once instead of the user re-deriving it for 30 turns.

Canonical files (read these, not template copies):

Entry points:

• .claude/BOOT.md — session entry point (one page).
• CLAUDE.md — workspace spec, links to all of the below.

Eight bookkeeping files (rows are history; specific fields are state; never delete a row; method hierarchy: APPEND preferred → Edit-field after prior Read → Write prompts for confirmation):

History / dashboards:

• .claude/board/LATEST_STATE.md — current contract inventory.
• .claude/board/PR_ARC_INVENTORY.md — APPEND-ONLY per-PR arc.
• .claude/board/STATUS_BOARD.md — deliverable-level dashboard.
• .claude/board/INTEGRATION_PLANS.md — versioned plan index.

Kanban / audit (priority + scope tags on every entry):

• .claude/board/EPIPHANIES.md — date-prefixed insight log. Status: FINDING / CONJECTURE / SUPERSEDED.
• .claude/board/ISSUES.md — Open + Resolved bugs / regressions. Double-entry: issue captured on discovery; Resolution appends on close. Priority P0-P3, Scope @agent D<N> domain:<tag>.
• .claude/board/IDEAS.md — Open + Implemented + Rejected speculation. Triple-entry: idea captured, shipped appended, plan-update logged. Priority + Scope.
• .claude/board/TECH_DEBT.md — Open + Paid knowingly-deferred work. Priority + Scope + Introduced-by-PR + Payoff-estimate.

Agent ensemble + orchestration:

• .claude/agents/BOOT.md — orchestration spec + Knowledge Activation + Handover Protocol.
• .claude/agents/README.md — function inventory of all agents.

Governance + hooks:

• .claude/settings.json — team-shared governance (ask-on-Edit for the two strictest bookkeeping files, deny on destructive ops, SessionStart + PostCompact hooks).
• .claude/hooks/session-start.sh / post-compact.sh — inject bootload context at turn 0 / after compaction.

Active plans:

• .claude/plans/<name>-v<N>.md — indexed via INTEGRATION_PLANS.md. Old versions stay with Status annotation; new versions prepend.

What to read when

• New session on this workspace: .claude/BOOT.md first, then the three mandatory reads it lists.
• Understanding the A2A two-layer model: concepts.md.
• Comparing to official Claude Code conventions: divergence.md.
• Concrete recipe: code awareness in ~90 s via prompt↔PR ledger: procedure-bookkeeping.md. Three-pass Haiku→Opus→main-thread pipeline. First deployment: PR #213 (lance-graph, 41 prompts) + PR #110 (ndarray, 25 prompts) on 2026-04-19, both ~90 s wall clock.

The idea in one paragraph

Every new session pays a 30-turn rediscovery tax rebuilding context about what types exist, which conventions are locked, what work is queued. CCA2A is the scaffold that cuts that to 3-5 turns: two mandatory knowledge files that state current inventory and decision history, one agent ensemble file that routes subagents, one hook that injects critical state after compaction. Append-only governance on the history files so drift can't erode the arc.

Source: AdaWorldAPI/lance-graph — distributed by TomeVault.