## Summary
- Preserve raw plugin skill-root snapshots in the matching loaded-plugin
cache entry, keyed by the effective plugin root identity including
namespace.
- Pass those snapshots through `SkillsLoadInput` as an optional preload,
so session startup reuses plugin parsing while ordinary skill loads pass
`None`.
- Keep plugin skill loading cohesive: the existing loaders accept the
optional snapshots directly, and uncached or marketplace-detail paths do
not create a cache.
## Why
Plugin discovery already parses plugin skills to determine available
capabilities. Cold session startup then scanned and parsed the same
roots again while building the skills snapshot.
This solves the same duplicate-work problem as #28623 while keeping
ownership narrow: `PluginsManager` creates and owns
`PluginSkillSnapshots` only for its loaded-plugin cache entry;
`SkillsService` consumes an optional clone. Entry replacement or
clearing naturally drops the snapshots, with no separate generation,
capacity policy, or watcher coupling.
## Validation
- `cargo clippy -p codex-core-skills --all-targets -- -D warnings`
- `just test -p codex-core-plugins
skills_service_reuses_skills_parsed_during_plugin_load`
- `just test -p codex-core-skills
namespaces_plugin_skills_using_provided_namespace`
- `just fmt`
## Why
`built_tools` runs for every sampling request, and local plugin
discovery was repeatedly rereading plugin manifests, skills, MCP
configuration, and app declarations to build the same tool-suggest
metadata.
That source-derived metadata is stable until the existing plugin manager
reloads its cache. Runtime eligibility still needs to reflect the
current install, disable, policy, app-overlap, and authentication state.
## What changed
- Add a bounded, in-memory tool-suggest metadata cache owned by
`PluginsManager`.
- Key cached metadata by plugin identity and source, while applying
authentication routing each time the metadata is projected.
- Invalidate the metadata alongside the existing loaded-plugin cache,
including its normal configuration, marketplace refresh, and
remote-installed-plugin invalidation paths.
- Guard against an in-flight load repopulating stale metadata after
invalidation.
- Keep marketplace membership and all runtime eligibility filtering live
rather than introducing a separate catalog or revision model.
## Impact
Repeated sampling requests reuse already-loaded plugin capability
metadata while retaining the existing plugin-manager lifecycle as the
single freshness boundary.
## Validation
- `just test -p codex-core-plugins` — 252 passed
- Added focused coverage for cache invalidation and authentication
reprojection.
xl-openai