feat(run-log): @agentic-kit/run-log — append-only agent run log, pi entries verbatim

[pyramation]

Summary

First package of the agent-kernel plan (planning#1655, #1657): the append-only run log that both placements (local pi, cloud pi job) write to and every surface reads from. Purely additive — no existing package touched, no new transport: the store is two interfaces, and the wire stays the GraphQL API / agent_event rows (durable Postgres impl lands later in constructive-db).

The load-bearing decision is no envelope re-encoding. pi entries are stored verbatim under a 4-field wrapper, so pi's own versioning/migrations keep working and a resumable session is just a projection:

{ runId, seq, recordedAt, piSessionVersion, entry /* untouched pi entry */ }

Everything else is a fold over RunEventRecord[]:

projector	output
projectParts	renderable transcript (text/thinking/tool/bash/custom/summary, unknown types preserved as unknown parts)
projectUsage	totals + per-provider/model breakdown from assistant usage.cost (observed usage for reconciliation, not billing authority)
projectToolState	tool lifecycle + pending approvals, where an approval is a pi custom message (constructive.approval.request/resolution) so it survives reconnects
projectSession	pi session JSONL → resume locally or in a restarted job

Read side is the polling contract the long-running FBP job needs — cursor in, page out, with an optional injected wakeup so LISTEN/NOTIFY can be dropped in later without touching consumers:

for await (const batch of follow(store, runId, { after: cursorAfter(seq), waitForChange, signal })) …

Bundling boundary is enforced by a test: src/index.ts and everything it reaches import no Node built-ins (browser/renderer safe); FileRunLogStore lives in src/file-store.ts and is imported explicitly.

Malformed input throws rather than degrading — assertRunEventRecord / assertOrdered reject mixed runs, non-increasing seq, mixed piSessionVersion, and truncated JSONL lines.

60 jest tests; agentic/run-log added to the agentic CI batch.

Link to Devin session: https://app.devin.ai/sessions/450ce6d6659c47759c184ae6ec19a2a8
Requested by: @pyramation

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