* fix: bound MCP server bring-up timeouts and exclude externalized tool outputs from delivery verification
Two related robustness fixes:
1. MCP server bring-up was unbounded. tool_call_timeout only covered
session.call_tool(); tool discovery (subprocess spawn + initialize +
tools/list) and persistent stdio session initialization could hang
forever, blocking agent construction (and on the Gateway event loop,
the whole process). Add a per-server session_init_timeout
(default DEFAULT_MCP_SESSION_INIT_TIMEOUT = 60s, null disables) that
bounds both discovery and pooled-session initialization. The session
pool's existing cancellation handling tears down a session stuck
mid-creation in its own task.
2. ToolOutputBudgetMiddleware externalizes oversized tool outputs into
outputs/.tool-results/ (configurable tool_output.storage_subdir). The
workspace-change scanner and run delivery verification counted those
files as produced artifacts, so any run that externalized a tool output
without also presenting a real artifact failed with
"Artifact delivery incomplete". Exclude TOOL_RESULTS_DIRNAME via a
shared constant (mirroring BROWSER_FRAMES_DIRNAME) and thread the
configured storage_subdir through snapshot capture so both
workspace-changes events and delivery verification stay clean.
* review: enforce single-segment tool_output.storage_subdir; document discovery-timeout cleanup
Address review feedback:
1. A custom tool_output.storage_subdir with a path separator (e.g.
cache/tool-results) silently no-oped the workspace-scanner exclusion:
os.walk yields one-segment dirnames, so a nested value never matched and
its files were counted as produced artifacts again. ToolOutputConfig now
validates storage_subdir as a single directory name (rejects separators,
.., absolute, empty) with tests, so the exclusion is always sound.
2. The discovery-timeout path now documents why cancellation is safe, mirroring
the session-init note: discovery runs inside the adapter's nested async
context managers, and stdio_client's finally terminates the process tree
(SIGTERM->SIGKILL on POSIX, process-tree on Windows), so a timed-out npx
subprocess and its children are reaped rather than accumulating.
* review: log session-init timeouts and align API response model default with runtime config
Address second-round review feedback:
1. A session-init timeout raised TimeoutError without any log, unlike the
discovery timeout which logs a WARNING. Wrap the bounded get_session in a
try/except that logs the timeout (server name + seconds) and re-raises, so
operators can diagnose tool-call failures caused by hung MCP sessions.
2. McpServerConfigResponse.session_init_timeout defaulted to None while
McpServerConfig defaults to 60s: a server created via PUT /api/mcp/config
without the field was persisted with null (no timeout) while the same
server created in the config file got 60s. Align the response-model default
to DEFAULT_MCP_SESSION_INIT_TIMEOUT so API-created and file-created servers
behave the same; an explicit null still opts out.
* review: narrow the discovery-timeout handler to the bounded wait_for path
The except TimeoutError clause covered both the bounded wait_for branch and
the bare discovery branch. With session_init_timeout opted out (None), a
TimeoutError raised by discovery itself would hit the %.1f format with None:
logging raises TypeError internally, the WARNING is silently dropped, and a
--- Logging error --- traceback goes to stderr.
Narrow the handler to wrap only the wait_for call, where the branch condition
guarantees the timeout value is not None. A discovery-internal TimeoutError on
the opted-out path now falls through to the generic failure handler and is
reported as 'tool discovery failed' with exc_info. Covered by a regression
test that asserts the skip is reported without any broken format.
