GitHub mirror ingestion should avoid full Linear issue scans

[miyaontherelay]

Problem

Factory GitHub issue ingestion currently performs a full /linear/issues mirror-candidate scan during startup/backfill. In the live workspace this took roughly 100 seconds before it could finish processing 29 GitHub issues from relayfile-adapters, and the full factory canary run took about 4 minutes.

Observed logs:

[factory] Linear mirror candidate loading started
[factory] relayfile listTree completed ... "prefix":"/linear/issues" ... "count":819
[factory] Linear mirror candidate loading completed {"elapsedMs":106660,"scanned":187,"candidates":186}

The scan makes the command look stuck even when it is progressing, and it will get worse as /linear/issues grows.

Expected

GitHub mirror dedupe should avoid reading broad Linear issue sets on every run. Possible directions:

• first check deterministic factory-create-github-<hash>.json draft paths
• maintain/cache a source-provider index for GitHub mirrors
• use a narrower /linear/issues query/alias if relayfile exposes one
• only fall back to full scan when deterministic paths/cache miss

Related

• Factory GitHub mirror dispatch PR: Fix GitHub issue mirror dispatch #25
• Live verified issue: Linear AR-311, source AgentWorkforce/relayfile-adapters#224