Capability primitive #2 (task #117). The first cross-cutting capability
where the adapter actually displaces platform behavior — claude-code's
streaming session can legitimately go silent for 8+ minutes during
synthesis + slow tool calls; the platform's hardcoded 5min idle timer
in a2a_proxy.go cancels it mid-flight (the bug PR #2128 patched at
the env-var layer). This PR fixes it at the right layer: the adapter
declares "I need 600s" and the platform's dispatch path honors it.
Wire shape (Python → Go):
POST /registry/heartbeat
{
"workspace_id": "...",
...
"runtime_metadata": {
"capabilities": {"heartbeat": false, "scheduler": false, ...},
"idle_timeout_seconds": 600 // optional, omitted = use default
}
}
Default behavior preserved: any adapter that doesn't override
BaseAdapter.idle_timeout_override() (returns None by default) sends
no idle_timeout_seconds field; the Go side falls through to
idleTimeoutDuration (env A2A_IDLE_TIMEOUT_SECONDS, default 5min).
Existing langgraph / crewai / deepagents workspaces are unaffected.
Components:
Python:
- adapter_base.py: idle_timeout_override() method on BaseAdapter
returning None (the platform-default sentinel).
- heartbeat.py: _runtime_metadata_payload() lazy-imports the active
adapter and assembles the capability + override block. Try/except
swallows ANY error so heartbeat never breaks because of capability
discovery — observability outranks capability accuracy.
Go:
- models.HeartbeatPayload.RuntimeMetadata (pointer so absent =
"old runtime, didn't say"; explicit zero-cap = "new runtime,
declared no native ownership").
- handlers.runtimeOverrides: in-memory sync.Map cache keyed by
workspaceID. Populated by the heartbeat handler, consulted on
every dispatchA2A. Reset on platform restart (worst-case 30s of
platform-default behavior — acceptable; nothing about overrides
is correctness-critical).
- a2a_proxy.dispatchA2A: looks up the override before applyIdle
Timeout; falls through to global default when absent.
Tests:
Python (17, all new):
- RuntimeCapabilities dataclass shape (frozen, defaults, wire keys)
- BaseAdapter.capabilities() default + override + sibling isolation
- idle_timeout_override default, positive override, dropped-override
- Heartbeat metadata producer: default adapter emits all-False,
native adapter emits flag + override, missing ADAPTER_MODULE
returns {} (graceful), zero/negative override is omitted from
wire, exception inside adapter swallowed
Go (6, all new):
- SetIdleTimeout + IdleTimeout round-trip
- Zero/negative duration clears the override
- Empty workspace_id ignored
- Replacement (heartbeat overwrites prior value)
- Reset clears entire cache
- Concurrent reads + writes (sync.Map invariant)
Verification:
- 1308 / 1308 workspace pytest pass (was 1300, +8)
- All Go handlers tests pass (6 new + existing)
- go vet clean
See project memory `project_runtime_native_pluggable.md` for the
architecture principle this implements.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
0d3058585b