## What changed
Extend `mcp_connection_sharing` to pool compatible local stdio connections that negotiate MCP `2026-07-28`. Keep legacy servers and servers that request input during startup private.
Preserve each chat's tool catalog and route input requests to the calling chat. Release connections independently for each chat, shutting down the shared server after the final release, and retire pooled connections on forced refresh without interrupting other chats.
## Testing
Add pool, runtime, app-server, and core scenario tests covering protocol gating, startup cancellation, refresh, final-release shutdown, and separate tool visibility and simultaneous input responses across chats sharing one process.
GitOrigin-RevId: 896b107267a20ec1bffccdefca6c40fe2945a022
## Why
MCP catalog discovery must not allow a server to keep pagination running or
growing without bounds.
## What changed
- Apply the shared pagination collector to tool, resource, and resource-template
discovery.
- Limit each catalog to 100 pages and 1,024 items, and reject pagination cursors
larger than 64 KiB or any repeated cursor.
- Bound the entire pagination operation by the configured tool timeout, falling
back to 30 seconds when no timeout is configured.
## Testing
Add unit coverage for every limit and an end-to-end MCP test that preserves
valid multi-page tools while excluding a server that returns an oversized
cursor.
GitOrigin-RevId: 961a1bfa5fe8a265daf56e342a919c980cd720fa
## What changed
- Add an opt-in `mcp_2026_07_28` protocol mode while preserving the legacy
lifecycle by default.
- Negotiate the new protocol over streamable HTTP with `server/discover`,
including bounded responses, redirect protection, and fallback only when a
response establishes that the endpoint is legacy-only.
- Require stdio servers to opt in with
`CODEX_MCP_PROTOCOL_VERSION=2026-07-28`, and add a bounded local stdio
transport for the modern lifecycle.
- Consume paginated tool, resource, and resource-template catalogs in modern
mode, reject repeated cursors, and retain discovered server identity.
- Reconnect reusable MCP clients when their selected protocol mode changes.
## Testing
- Cover HTTP JSON and SSE discovery, legacy fallback and rejection cases,
redirects, retries, response limits, and pagination.
- Cover local and executor stdio discovery, protocol markers, message limits,
and legacy compatibility.
GitOrigin-RevId: f6a78816e127d2a482292d63b91c8384f1595903
## What changed
- Make `McpResourceClient` resolve resource operations and cache identity from
the latest `McpRuntime` connection snapshot.
- Remove step-bound resource clients from `McpBinding` and the associated
per-binding client identity tracking.
GitOrigin-RevId: ee59f5867308c5a63e6e232384a50cf1e0c2a011
## Why
An MCP connection or tool catalog can change after a model step captures its
available tools. Calls from that step must not be rerouted to a replacement
client or run against a catalog revision the model did not see.
## What changed
- Add `McpBinding` to capture the ready clients, visible tools, resources, and
server metadata for one sampling request.
- Prepare calls against the captured client and reject them if the tool catalog
changes before call preparation and execution finish.
- Keep resource access and cache identity tied to the binding's exact connection
set, and omit servers that do not have a ready client.
- Preserve each client's unfiltered tool catalog so bindings can apply the
current filter consistently.
## Testing
Add coverage for connection replacement, stale catalog rejection, serialized
call preparation and refresh, ready-client capture, and binding-scoped resource
identity.
GitOrigin-RevId: a25da4d2c7f5ed06c41caa0c6d15c464c1698314
## What changed
- Add `McpBindingClients` to hold the ready MCP clients captured for a model step.
- Move concurrent, paginated resource and resource-template listing into the new helper.
- Keep server filtering in `McpConnectionManager` while preserving per-client timeouts, duplicate-cursor detection, and warning behavior.
GitOrigin-RevId: 0e3f8f135126b17d73058ca84e98493a27543ca0
Charlie Marsh