## Why
Dedicated memories tools are exposed through a Responses API namespace
tool. The namespace itself has to be a valid tool identifier, so
`memories/` can fail validation before the model ever gets a chance to
call the memory tools.
## What changed
- Changed `MEMORY_TOOLS_NAMESPACE` from `memories/` to `memories`.
- Added `memory_tool_namespace_matches_responses_api_identifier` so the
namespace stays non-empty and limited to Responses-safe identifier
characters.
## Verification
- Added unit coverage for the namespace identifier shape in
`codex-rs/ext/memories/src/tests.rs`.
## Why
The memories extension now receives a metrics exporter, but the useful
extension-owned signal is the memory tool call itself: which operation
ran, which memory area it touched, whether the backend call succeeded,
and whether the result was truncated.
## What changed
- Added the `codex.memories.tool.call` counter in
`ext/memories/src/metrics.rs`.
- Emit that counter from `memories/add_ad_hoc_note`, `memories/list`,
`memories/read`, and `memories/search` after backend execution.
- Tag each call with `tool`, `operation`, `scope`, `status`, and
`truncated`.
- Pass the existing `MetricsClient` through the memories extension into
the tool executors; tests use `None`.
## Verification
- `just test -p codex-memories-extension`
## Why
Codex memory updates currently rely on instructions that tell agents to
create ad-hoc note files directly in the memory workspace. The memories
extension already has a `MemoriesBackend` abstraction for local storage
and future non-filesystem backends, so the ad-hoc note writer should
live behind that same interface instead of baking local filesystem
assumptions into the tool shape.
## What
- Adds a `memories/add_ad_hoc_note` tool to the existing memories tool
bundle.
- Extends `MemoriesBackend` with `add_ad_hoc_note` plus request/response
types so remote memory stores can implement the same operation later.
- Implements the local backend by creating append-only notes under
`extensions/ad_hoc/notes`.
- Validates the tool-provided filename contract
(`YYYY-MM-DDTHH-MM-SS-<slug>.md`), rejects path-like filenames, rejects
empty notes, and uses create-new semantics so existing notes are never
overwritten.
- Keeps memories tool contribution behind the existing commented-out
registration path; this defines the tool surface without newly exposing
it through app-server.
## Test Plan
- `just test -p codex-memories-extension`
## Why
The memories extension now owns the read-path developer instructions it
injects at thread start. Keeping that prompt builder and template in
`codex-memories-read` left the extension depending on a helper crate for
extension-specific prompt assembly, and kept async template/truncation
dependencies in the read crate after the remaining read surface no
longer needed them.
## What changed
- Moved `prompts.rs`, its tests, and `templates/memories/read_path.md`
from `memories/read` into `ext/memories`.
- Wired `MemoryExtension` to call the local prompt builder and added the
moved templates to `ext/memories/BUILD.bazel` compile data.
- Removed the now-unused prompt export and prompt-related dependencies
from `codex-memories-read`.
## Testing
- Not run locally.
## Why
The memories extension has several distinct responsibilities:
registering its prompt and tool contributors, enforcing local-memory
filesystem boundaries, implementing list/read/search behavior, and
wrapping that backend as extension tools. Those responsibilities were
concentrated in `lib.rs`, `local.rs`, and the tool modules, which made
follow-up work harder to review and risked growing files through
unrelated edits.
This PR reorganizes the crate so each responsibility has a narrower
owner while preserving the same extension entrypoint and memory tool
behavior.
## What Changed
- Moved extension lifecycle, prompt, and tool registration into
`src/extension.rs`, leaving `src/lib.rs` as the small crate entrypoint.
- Split `LocalMemoriesBackend` helpers into `local/list.rs`,
`local/path.rs`, `local/read.rs`, and `local/search.rs`.
- Centralized tool names and limits at the crate level, and kept the
backend and extension implementation crate-private.
- Made `memory_list`, `memory_read`, and `memory_search` tool executors
generic over `MemoriesBackend`, so tests can exercise the full executor
path without depending on tool internals.
- Consolidated and expanded memory extension tests in `src/tests.rs`,
including read/search tool output coverage, multi-query search, windowed
`all_within_lines`, and legacy `query` rejection.
## Testing
- Not run locally.