Self-review (post-merge) flagged that the backfill claimed to be
idempotent on re-run but actually duplicates every row because the
plugin's INSERT uses gen_random_uuid() and ignores any id passed in.
Fix is contract-level: extend MemoryWrite with an optional `id`
idempotency key. When supplied, the plugin MUST treat the write as
upsert keyed on this id; when omitted, the plugin generates a fresh
UUID (production agent commits keep working unchanged).
Changes:
* docs/api-protocol/memory-plugin-v1.yaml: add id field with
description that flags it as idempotency key
* internal/memory/contract/contract.go: add ID to MemoryWrite struct,
update memory_write_minimal golden vector
* internal/memory/pgplugin/store.go: split CommitMemory into two
paths — upsert when body.ID set (INSERT ... ON CONFLICT (id) DO
UPDATE), plain INSERT otherwise
* cmd/memory-backfill/main.go: pass agent_memories.id to MemoryWrite,
fix the false comment about 409 deduplication
New tests:
* pgplugin: TestCommitMemory_WithIDUpserts pins the upsert SQL is
used when id is set; TestCommitMemory_UpsertScanError covers the
error branch
* backfill: TestBackfill_PassesSourceUUIDAsIdempotencyKey pins the
forwarding behavior; TestBackfill_RerunIsIdempotent simulates a
retry and asserts both runs pass the same uuid (plugin upsert is
what makes this safe)
Why this matters: operators retrying a failed backfill (which they
will — networks fail, transactions abort) would otherwise create N
duplicates per memory. The duplicates aren't visible until search
results show obvious dupes — debugging that under prod load is bad.
Production agent commits are unaffected: they leave id empty, the
plugin generates a fresh UUID via gen_random_uuid(), zero behavior
change for the hot path.
1e97fb9a16