feat(campaign): Lineage DAG — git-graph of candidates, multi-parent merges, visioned tracks, agent-managed governor

[drewstone]

The foundation for the multi-track / archive / customer-inbox vision. Today the improvement loop records a linear history with no parent pointers and collapses its within-run frontier to one gated winner. This adds the DAG.

What it is

• Lineage DAG — nodes carry parentIds[]: 0 = root, 1 = mutation, 2+ = MERGE (collapse). A merge is not special-cased — it's just a multi-parent node the governor decides to create ("collapsing is a feature of the graph the supervisor chooses").
• Visioned tracks (islands) — each track runs a distinct vision (proposer strategy): solve / outside-the-box / an adversarial contrarian that attacks the leader. This is the "solve N different ways + one tries to disprove it" pattern as first-class tracks — a usage pattern, not new plumbing.
• Agent-managed Governor — extend / branch / merge / prune / stop. heuristicGovernor is the deterministic reference policy; callbackGovernor is the LLM-supervisor slot (reads lineage.toGraph()).
• runLineage orchestration + fs/mem persistence (append-only JSONL, resumable across runs).
• Determinism enforced — no Date.now/Math.random/new Date; content-hash ids; monotone seq; seq-sorted queries. End-to-end re-run yields an identical graph.
• Acyclic by construction (parents pre-exist + immutable ids + append-only), not a runtime guard; traversal stays cycle-safe on corrupted deserialized input.

Tests — 24/24

id determinism; generation derivation; idempotent add; acyclic invariant + traversal safety; diamond merge with ancestors/descendants; scalar + Pareto frontier (dominated tip excluded); JSONL round-trip; fs store in a tmp dir; governor extend/merge/prune/stop + determinism; end-to-end 3-vision run producing a merge, honoring prune, identical on re-run.

Additive; no existing behavior touched. Next: wire real step/merge seams (runImprovementLoop + GEPA crossover) for the first live multi-track run.

[tangletools]

✅ Auto-approved drewstone PR — 0b5780f9

This PR was opened by the trusted drewstone account.
The full PR reviewer audit still runs separately and will publish findings if it detects issues.

_{tangletools · auto-approval · reason: drewstone_author · 2026-07-07T02:32:17Z}