fix(mcp): scrub err.Error() from JSON-RPC error messages (OFFSEC-001)

Replace all three err.Error() leaks in mcp.go with constant strings,
consistent with the same fix applied to 22 other files in PRs #1193/1206/1219/#168.

- Call handler (line ~329): "parse error: " + err.Error() → "parse error"
- dispatchRPC params unmarshal (line ~417): "invalid params: " + err.Error()
  → "invalid parameters"
- dispatchRPC tool call (line ~422): err.Error() → "tool call failed"
  + log.Printf server-side for forensics

Routes protected by WorkspaceAuth (C1) and MCPRateLimiter (C2) — this is
defence-in-depth per OFFSEC-001 / #259.

Tests added:
- TestMCPHandler_Call_MalformedJSON_ReturnsConstantParseError
- TestMCPHandler_dispatchRPC_InvalidParams_ReturnsConstantMessage
- TestMCPHandler_dispatchRPC_UnknownTool_ReturnsConstantMessage
- TestMCPHandler_dispatchRPC_InvalidParams_ArrayInsteadOfObject

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

.gitea/workflows/publish-workspace-server-image.yml

@@ -23,7 +23,7 @@ name: publish-workspace-server-image
 
 on:
   push:
-    branches: [main]
+    branches: [staging, main]
     paths:
       - 'workspace-server/**'
       - 'canvas/**'
@@ -32,9 +32,11 @@ on:
       - '.gitea/workflows/publish-workspace-server-image.yml'
   workflow_dispatch:
 
-# Serialize per-branch so two rapid main pushes don't race the same
-# :staging-latest tag retag. Allow parallel runs as they produce
-# different :staging-<sha> tags and last-write-wins on :staging-latest.
+# Serialize per-branch so two rapid staging pushes don't race the same
+# :staging-latest tag retag. Allow staging and main to run in parallel
+# (different GITHUB_REF → different concurrency group) since they
+# produce different :staging-<sha> tags and last-write-wins on
+# :staging-latest is acceptable across branches.
 #
 # cancel-in-progress: false → in-flight builds finish; the next push's
 # build queues. This avoids a partially-pushed image.

.github/workflows/publish-workspace-server-image.yml

@@ -32,7 +32,7 @@ name: publish-workspace-server-image
 
 on:
   push:
-    branches: [main]
+    branches: [staging, main]
     paths:
       - 'workspace-server/**'
       - 'canvas/**'

.staging-trigger

@@ -1 +0,0 @@
-staging trigger

docs/agent-runtime/workspace-runtime.md

@@ -269,28 +269,6 @@ Each workspace exposes an A2A server, builds an Agent Card, and registers with t
 
 But the long-term collaboration model remains direct workspace-to-workspace communication via A2A.
 
-## Known Limitations
-
-### Playwright / browser system libs are not installed
-
-The base `molecule-ai-workspace-runtime` image (`workspace/Dockerfile`) is built on `python:3.11-slim` with Node.js 22, git, and `gh` — about 500 MB. It deliberately **does not** include the system libraries Chromium needs (`libnss3`, `libatk-bridge2.0-0`, `libxkbcommon0`, `libcups2`, `libdrm2`, `libxcomposite1`, `libxdamage1`, `libxrandr2`, `libgbm1`, `libpango-1.0-0`, `libasound2`, etc.). Adding them would inflate the image by ~200–250 MB (~40%) for every workspace, even though only frontend / QA workspaces ever launch a browser.
-
-Practical consequences:
-
-- `npx playwright test` (and any other Chromium-driven E2E tooling) **will fail at browser launch** when run from inside an in-container workspace agent.
-- The error surface is missing-shared-object messages such as `error while loading shared libraries: libnss3.so` or `Host system is missing dependencies to run browsers`.
-- Unit and integration tests (Vitest, Jest, etc.) that don't spawn a real browser are unaffected.
-
-Recommended workflow:
-
-1. **Run E2E in CI**, not in-container. The Gitea Actions self-hosted runner (and the GitHub Actions runner used by mirror repos) has the full Playwright dep set installed and is the supported surface for E2E. Push a branch, let CI run the suite.
-2. **Local debugging** of a single failing spec is best done on a developer laptop with `npx playwright install-deps` run once.
-3. **In-container iteration** on test logic itself is fine — write specs, lint them, type-check them — just don't expect `playwright test` to actually launch a browser.
-
-If a particular workspace role genuinely needs in-container E2E (a dedicated QA template, for instance), the right place to layer Playwright deps is in a **role-specific adapter template image** that does `FROM molecule-ai-workspace-runtime:<tag>` and adds `RUN npx playwright install-deps`. Open a request against `molecule-ai-workspace-runtime` if you need this template stamped.
-
-Tracking issue: [molecule-ai/molecule-app#7](https://git.moleculesai.app/molecule-ai/molecule-app/issues/7).
-
 ## Related Docs
 
 - [Agent Runtime Adapters](./cli-runtime.md)

manifest.json

@@ -44,4 +44,3 @@
     {"name": "mock-bigorg", "repo": "molecule-ai/molecule-ai-org-template-mock-bigorg", "ref": "main"}
   ]
 }
-// Triggered by Integration Tester at 2026-05-10T08:52Z

workspace/a2a_response.py

@@ -179,23 +179,6 @@ def parse(data: Any) -> Variant:
         )
         return Malformed(raw=data)
 
-    # Push-mode queue envelope — returned when a push-mode workspace
-    # (one with a public URL) is at capacity. The platform queues the
-    # request and returns {"queued": true, "message": "...", "queue_id": "..."}.
-    # Unlike the poll-mode envelope (status=queued + delivery_mode=poll),
-    # this shape has no delivery_mode key — it's distinguishable by
-    # data.get("queued") is True alone. Checked before poll-mode so the
-    # two cases are mutually exclusive even if a buggy server sends both.
-    if data.get("queued") is True:
-        method_raw = data.get(_KEY_METHOD)
-        method = str(method_raw) if method_raw is not None else "message/send"
-        logger.info(
-            "a2a_response.parse: queued for busy push-mode peer (method=%s, queue_id=%s)",
-            method,
-            data.get("queue_id", "?"),
-        )
-        return Queued(method=method)
-
     # Poll-queued envelope. Both keys must be present — the workspace
     # server sets them together; if only one is present the body is
     # ambiguous and we route to Malformed for visibility.

workspace/builtin_tools/a2a_tools.py

@@ -66,23 +66,10 @@ async def delegate_task(workspace_id: str, task: str) -> str:
             )
             data = a2a_resp.json()
             if "result" in data:
-                result = data["result"]
-                parts = result.get("parts", []) if isinstance(result, dict) else []
-                if parts and isinstance(parts[0], dict):
-                    return parts[0].get("text", "(no text)")
-                return str(result) if isinstance(result, str) else "(no text)"
+                parts = data["result"].get("parts", [])
+                return parts[0].get("text", "(no text)") if parts else str(data["result"])
             elif "error" in data:
-                err = data["error"]
-                # Handle both string-form errors ("error": "some string")
-                # and object-form errors ("error": {"message": "...", "code": ...}).
-                msg = ""
-                if isinstance(err, dict):
-                    msg = err.get("message", "")
-                elif isinstance(err, str):
-                    msg = err
-                else:
-                    msg = str(err)
-                return f"Error: {msg}"
+                return f"Error: {data['error'].get('message', str(data['error']))}"
             return str(data)
         except Exception as e:
             return f"Error sending A2A message: {e}"