## Why
Transient executor disconnects could leave capability discovery and skill catalogs
stuck on a cached failure for the rest of a thread, even after the executor
reconnected.
## What changed
- Replay capability discovery after executor recovery and retry transient failures
on later requests while continuing to cache permanent failures.
- Avoid caching skill catalogs produced from failed discovery so a later step can
load the recovered catalog.
- Mark the MCP runtime dirty when recovered manifests change the projected MCP
servers, and allow discovery to be cancelled with the turn.
## Testing
- Cover same-request recovery after a disconnect and recovery on a later request.
- Cover retry classification through connection-attempt errors and skill catalog
caching after discovery recovers.
GitOrigin-RevId: a57f90844351e73ea831931f72a9ddc4e4f3335c
## Why
Executor capability discovery can traverse plugin and skill roots, including
symlinks. Under restricted filesystem permissions, discovery must not expose
files outside the permitted paths.
## What changed
- Pass each environment's filesystem sandbox context through capability root
discovery and apply it to metadata, directory walks, and file reads.
- Enable discovery for restricted sessions so permitted executor skills remain
available while inaccessible roots and symlink targets are omitted.
- Key discovery caches by sandbox context and reject sandboxed discovery on
executors that do not advertise support for it.
- Split requests with more than 128 roots into supported-size batches.
## Testing
- Cover permitted and denied external symlink targets.
- Verify restricted skill listing excludes inaccessible skills.
- Verify cache separation across permission contexts and discovery of 129 roots.
GitOrigin-RevId: 44d16468ca003403bdb8b71a04ae8c9ff94ed494
## Why
Selected capability roots can contribute plugins, MCP servers, connectors, and
skills. Discovering each contribution separately requires repeated access to the
executor filesystem.
## What changed
- Add the `capabilityRoots/discoverV1` exec-server RPC to scan selected roots and
materialize recognized plugin manifests, configuration files, skill
instructions, and skill metadata in one bounded request.
- Add the opt-in `executor_capability_discovery` feature, with a thread-scoped
cache and per-step snapshot shared by MCP and skill discovery.
- Parse MCP, connector, and skill contributions from the materialized snapshot,
including serving cached skill instructions without another filesystem read.
## Testing
- Cover discovery limits, manifest precedence, root-local failures, cache reuse,
plugin contributions, and parity with the existing environment skill loader.
GitOrigin-RevId: f98fd2321cafb58c596db02da1f83c09d8eb375d
