Memory retrieval was partitioned only by `x-headroom-user-id`. Claude
Code never sets that header, so every project a user worked on landed
in one global `default` bucket; the proxy then injected semantically
similar memories from that mixed bucket into every `/v1/messages`
request, regardless of which repo the session was actually about. The
injected `## Relevant Memories` block reads like a prompt-injection
payload and Claude has been seen to refuse to act on it, defeating the
feature.
This change makes leakage structurally impossible by giving each
resolved workspace its own SQLite database file. The wrong DB is
simply not open during a request.
- `headroom/memory/storage_router.py` (new) — `MemoryStorageMode`
(project/user/global), `ProjectResolver` (x-headroom-project-id →
x-headroom-cwd → --memory-project-root CLI override → env-block
parse: `Primary working directory:` / `Working directory:` / `cwd:`,
no regex), and `BackendRouter` with an LRU of open `LocalBackend`s
keyed by db_path.
- `proxy/memory_handler.py` — `MemoryConfig.storage_mode` defaults to
`PROJECT`. Provider handlers build a `RequestContext` once and pass
it through; `search_and_format_context`, `handle_memory_tool_calls`,
and the `_execute_*` methods route save/search/update/delete on the
per-project backend. Qdrant-neo4j gets a composite
`user::project_key` partition so external Mem0-style deployments
also isolate per project without a parallel collection.
- Fix C — injected block carries provenance:
`## Relevant Memories (workspace: <basename>, scope: project)`.
CCR proactive-expansion block gets a matching workspace tag.
- `memory/factory.py` — process-wide embedder cache so opening N
project DBs doesn't load the embedder N times. OpenAI key
validation runs ahead of the cache.
- CLI — `--memory-storage={project,user,global}` (default `project`),
`--memory-project-root` override, rewritten `--memory` help text,
banner reports storage mode.
- Migration UX — if the legacy single-file DB has content while
project mode is active, an INFO log points users at
`--memory-storage=global`. Bridge currently only syncs the legacy
DB; a WARN fires when bridge + project mode are combined.
Backward-compatible: legacy `~/.headroom/memory.db` untouched and
reachable via `--memory-storage=global`. `request_context` is
keyword-only on entry points so existing tests/mocks keep working.
Tests: 24 new (resolver tiers, LRU eviction, two-cwd isolation,
user-mode partition, legacy fallback, provenance headers); full
suite 5260 passing, ci-precheck green.
