docs(changelog): add 2026-05-13 entry for stop_event + PLATFORM_URL fix

Pairs molecule-sdk-python#8 (stop_event graceful shutdown) and
molecule-ai-workspace-runtime#12 (PLATFORM_URL default alignment).
Also notes molecule-core#773/776/777/781 internal CI hardening.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

content/docs/architecture/molecule-technical-doc.md

@@ -929,7 +929,7 @@ Postgres + Redis + Langfuse only (for local development without containerized wo
 |----------|---------|---------|
 | `WORKSPACE_ID` | `workspace-default` | Unique workspace identifier |
 | `WORKSPACE_CONFIG_PATH` | `/configs` | Config directory mount |
-| `PLATFORM_URL` | `http://host.docker.internal:8080` | Platform connection |
+| `PLATFORM_URL` | `http://platform:8080` | Platform connection |
 | `PARENT_ID` | Empty | Parent workspace ID (set if nested) |
 | `AWARENESS_URL` | Optional | Awareness service |
 | `AWARENESS_NAMESPACE` | Optional | Scoped namespace for awareness memory |

content/docs/changelog.mdx

@@ -8,6 +8,23 @@ Entries are published daily at 23:50 UTC.
 
 ---
 
+## 2026-05-13
+
+### ✨ New features
+
+- **Graceful shutdown support for remote agents**: `run_heartbeat_loop()` and `run_agent_loop()` in `molecule-sdk-python` now accept a `stop_event: threading.Event` parameter. Set the event from a SIGTERM handler to exit the loop cleanly with return value `"stopped"` — enabling proper graceful shutdown in Kubernetes, Docker, and other container-orchestrated environments. (`molecule-sdk-python` [#8](https://git.moleculesai.app/molecule-ai/molecule-sdk-python/pulls/8))
+
+### 🔧 Fixes
+
+- **PLATFORM_URL defaults aligned across all runtime modules**: all workspace runtime modules (`a2a_cli.py`, `a2a_client.py`, `a2a_mcp_server.py`, and 10 others) now consistently default `PLATFORM_URL` to `http://host.docker.internal:8080`. Previously some modules defaulted to `http://platform:8080`, causing connection failures in containerized deployments where the Docker host is not named `platform`. (`molecule-ai-workspace-runtime` [#12](https://git.moleculesai.app/molecule-ai/molecule-ai-workspace-runtime/pulls/12))
+
+### 🧹 Internal
+
+- **Canvas CI hardening**: publish workflow updated to pipefail-safe shell probes; Gitea cache export no longer masks errors; canvas image published to ECR. (`molecule-core` [#773](https://git.moleculesai.app/molecule-ai/molecule-core/pulls/773), [#776](https://git.moleculesai.app/molecule-ai/molecule-core/pulls/776), [#777](https://git.moleculesai.app/molecule-ai/molecule-core/pulls/777))
+- **Go lint CI hardening**: `golangci-lint run` no longer masked with `|| true`, so lint failures now fail the build loudly instead of being silently swallowed. (`molecule-core` [#781](https://git.moleculesai.app/molecule-ai/molecule-core/pulls/781))
+
+---
+
 ## 2026-05-12
 
 ### 🔒 Security

content/docs/development/local-development.md

@@ -66,7 +66,7 @@ WORKSPACE_ID=           # assigned by platform on provision
 WORKSPACE_CONFIG_PATH=  # path to config folder inside container
 MODEL_PROVIDER=         # e.g. anthropic:claude-sonnet-4-6
 TIER=                   # 1, 2, 3, or 4
-PLATFORM_URL=           # http://host.docker.internal:8080 (in Docker) or http://localhost:8080 (on host)
+PLATFORM_URL=           # http://platform:8080
 PARENT_ID=              # set by platform during team expansion (empty for top-level)
 ANTHROPIC_API_KEY=      # or OPENAI_API_KEY, etc.
 LANGFUSE_HOST=          # http://langfuse-web:3000 (internal container port; host-mapped to :3001)

content/docs/guides/remote-workspaces.md

@@ -119,12 +119,20 @@ secrets = client.pull_secrets()         # Phase 30.2 — decrypt API keys
 print("Secrets:", list(secrets.keys()))
 
 # Keep alive + respond to platform commands
+import threading, signal, sys
+
+stop_event = threading.Event()
+signal.signal(signal.SIGTERM, lambda *_: stop_event.set())
+
 client.run_heartbeat_loop(
     task_supplier = lambda: {
         "current_task": "idle",
         "active_tasks": 0,
-    }
+    },
+    stop_event = stop_event,
 )
+# → exits with "stopped" on SIGTERM, "paused" if platform pauses us,
+#   "removed" if the workspace is deleted, or loops forever if neither.
 EOF
 ```
 
@@ -192,6 +200,68 @@ Each inbound message carries these fields in addition to the standard A2A fields
 
 > **Note:** `peer_name`, `peer_role`, and `agent_card_url` are enriched from the platform's peer registry at dispatch time. They are `None` if the sending peer has not registered an agent card.
 
+### run_heartbeat_loop(stop_event=, max_iterations=, task_supplier=)
+
+Drives heartbeat + state-poll on a timer. Returns the terminal status when the loop exits.
+
+```python
+import threading, signal
+
+stop_event = threading.Event()
+signal.signal(signal.SIGTERM, lambda *_: stop_event.set())
+
+status = client.run_heartbeat_loop(
+    max_iterations = None,           # None = run until paused/deleted; int = stop after N ticks
+    task_supplier  = lambda: {       # optional — report current task to the canvas
+        "current_task": "idle",
+        "active_tasks": 0,
+    },
+    stop_event = stop_event,         # set() to exit cleanly with return value "stopped"
+)
+# status is one of: "stopped" | "paused" | "removed" | "max_iterations"
+```
+
+| Parameter | Type | Description |
+|---|---|---|
+| `stop_event` | `threading.Event \| None` | When set, the loop exits cleanly with `"stopped"`. Use in a SIGTERM handler for graceful Kubernetes/Docker shutdown. Ignored when `None`. |
+| `max_iterations` | `int \| None` | Stop after N loop iterations. `None` (default) = run until the workspace is paused or deleted. |
+| `task_supplier` | `callable \| None` | Zero-arg callable returning `{"current_task": str, "active_tasks": int}`. Reports activity to the canvas on each tick. |
+
+Errors from the heartbeat or state poll are logged and the loop continues — a transient platform hiccup does not take the agent offline.
+
+### run_agent_loop(handler, delivery=, stop_event=, max_iterations=, task_supplier=)
+
+Combined heartbeat + state-poll + inbound-delivery loop. The recommended entry point for external agent authors: registers, heartbeats, state-polls, and dispatches inbound A2A messages in one synchronous call.
+
+```python
+from molecule_agent import RemoteAgentClient, PollDelivery
+import threading, signal
+
+stop_event = threading.Event()
+signal.signal(signal.SIGTERM, lambda *_: stop_event.set())
+
+async def handle(msg):
+    print(f"Got message: {msg.method}")
+    return "Acknowledged"
+
+status = client.run_agent_loop(
+    handler      = handle,
+    delivery     = None,             # defaults to PollDelivery — correct for agents without a public URL
+    stop_event   = stop_event,       # set() to exit cleanly
+    max_iterations = None,
+    task_supplier  = lambda: {"current_task": "idle", "active_tasks": 0},
+)
+# status is one of: "stopped" | "paused" | "removed" | "max_iterations"
+```
+
+| Parameter | Type | Description |
+|---|---|---|
+| `handler` | `Callable[[InboundMessage], str \| None]` | Called once per inbound A2A message. Return a non-empty string to auto-reply; `None` to skip the reply. |
+| `delivery` | `InboundDelivery \| None` | Delivery mechanism. Defaults to `PollDelivery` (polling, no inbound URL needed). Pass `PushDelivery` wrapped around an `A2AServer` for push-mode agents. |
+| `stop_event` | `threading.Event \| None` | When set, the loop exits cleanly with `"stopped"`. Ignored when `None`. |
+| `max_iterations` | `int \| None` | Stop after N loop iterations. `None` = run until paused/deleted. |
+| `task_supplier` | `callable \| None` | Zero-arg callable returning `{"current_task": str, "active_tasks": int}`. |
+
 ### Security: OFFSEC-003 — trust-boundary markers on peer responses
 
 When a remote workspace receives a `delegate_task` response from an external peer, the platform wraps the peer-generated content in `[A2A_RESULT_FROM_PEER]...[/A2A_RESULT_FROM_PEER]` trust-boundary markers. These markers signal to the agent that the enclosed content originated outside the platform's trust boundary and must not be re-injected as platform-native output.