fix(a2a): handle string-form errors in delegate_task

The A2A proxy can return three error shapes:
  {"error": "plain string"}
  {"error": {"message": "...", "code": ...}}
  {"error": {"message": {"nested": "object"}}}   ← value at .message is a string

builtin_tools/a2a_tools.py:72 called data["error"].get("message")
without guarding against error being a string, which raised:
  AttributeError: 'str' object has no attribute 'get'

This broke every delegation attempt through the legacy a2a_tools path
(the LangChain-wrapped version used by adapter templates). The
SSOT parser a2a_response.py already handled string errors; the
legacy inline sniffer in a2a_tools.py did not.

Fix: branch on isinstance(err, dict/str/other) before calling .get().

Also update both publish-workflow files to remove the dead
`staging` branch trigger — trunk-based migration (PR #109,
2026-05-08) removed the staging branch.

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: [staging, main]
+    branches: [main]
     paths:
       - 'workspace-server/**'
       - 'canvas/**'
@@ -32,11 +32,9 @@ on:
       - '.gitea/workflows/publish-workspace-server-image.yml'
   workflow_dispatch:
 
-# 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.
+# 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.
 #
 # cancel-in-progress: false → in-flight builds finish; the next push's
 # build queues. This avoids a partially-pushed image.

.github/workflows/publish-runtime.yml

@@ -180,7 +180,7 @@ jobs:
         # environment pypi-publish. The action mints a short-lived OIDC
         # token and exchanges it for a PyPI upload credential — no static
         # API token in this repo's secrets.
-        uses: pypa/gh-action-pypi-publish@release/v1
+        uses: pypa/gh-action-pypi-publish@cef221092ed1bacb1cc03d23a2d87d1d172e277b # release/v1
         with:
           packages-dir: ${{ runner.temp }}/runtime-build/dist/
 

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

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

.github/workflows/secret-pattern-drift.yml

@@ -48,7 +48,7 @@ jobs:
     runs-on: ubuntu-latest
     timeout-minutes: 5
     steps:
-      - uses: actions/checkout@v6
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
 
       - uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405 # v6.2.0
         with:

.staging-trigger

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

docs/agent-runtime/workspace-runtime.md

@@ -269,6 +269,28 @@ 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

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

workspace-server/go.mod

@@ -4,7 +4,6 @@ go 1.25.0
 
 require (
 	github.com/DATA-DOG/go-sqlmock v1.5.2
-	go.moleculesai.app/plugin/gh-identity v0.0.0-20260509010445-788988195fce
 	github.com/alicebob/miniredis/v2 v2.37.0
 	github.com/creack/pty v1.1.24
 	github.com/docker/docker v28.5.2+incompatible
@@ -19,6 +18,7 @@ require (
 	github.com/opencontainers/image-spec v1.1.1
 	github.com/redis/go-redis/v9 v9.19.0
 	github.com/robfig/cron/v3 v3.0.1
+	go.moleculesai.app/plugin/gh-identity v0.0.0-20260509010445-788988195fce
 	golang.org/x/crypto v0.50.0
 	gopkg.in/yaml.v3 v3.0.1
 )

workspace-server/go.sum

@@ -4,8 +4,6 @@ github.com/DATA-DOG/go-sqlmock v1.5.2 h1:OcvFkGmslmlZibjAjaHm3L//6LiuBgolP7Oputl
 github.com/DATA-DOG/go-sqlmock v1.5.2/go.mod h1:88MAG/4G7SMwSE3CeA0ZKzrT5CiOU3OJ+JlNzwDqpNU=
 github.com/Microsoft/go-winio v0.6.2 h1:F2VQgta7ecxGYO8k3ZZz3RS8fVIXVxONVUPlNERoyfY=
 github.com/Microsoft/go-winio v0.6.2/go.mod h1:yd8OoFMLzJbo9gZq8j5qaps8bJ9aShtEA8Ipt1oGCvU=
-github.com/Molecule-AI/molecule-ai-plugin-gh-identity v0.0.0-20260424033845-4fd5ac7be30f h1:YkLRhUg+9qr9OV9N8dG1Hj0Ml7TThHlRwh5F//oUJVs=
-github.com/Molecule-AI/molecule-ai-plugin-gh-identity v0.0.0-20260424033845-4fd5ac7be30f/go.mod h1:NqdtlWZDJvpXNJRHnMkPhTKHdA1LZTNH+63TB66JSOU=
 github.com/alicebob/miniredis/v2 v2.37.0 h1:RheObYW32G1aiJIj81XVt78ZHJpHonHLHW7OLIshq68=
 github.com/alicebob/miniredis/v2 v2.37.0/go.mod h1:TcL7YfarKPGDAthEtl5NBeHZfeUQj6OXMm/+iu5cLMM=
 github.com/bsm/ginkgo/v2 v2.12.0 h1:Ny8MWAHyOepLGlLKYmXG4IEkioBysk6GpaRTLC8zwWs=
@@ -154,6 +152,8 @@ github.com/yuin/gopher-lua v1.1.1 h1:kYKnWBjvbNP4XLT3+bPEwAXJx262OhaHDWDVOPjL46M
 github.com/yuin/gopher-lua v1.1.1/go.mod h1:GBR0iDaNXjAgGg9zfCvksxSRnQx76gclCIb7kdAd1Pw=
 github.com/zeebo/xxh3 v1.1.0 h1:s7DLGDK45Dyfg7++yxI0khrfwq9661w9EN78eP/UZVs=
 github.com/zeebo/xxh3 v1.1.0/go.mod h1:IisAie1LELR4xhVinxWS5+zf1lA4p0MW4T+w+W07F5s=
+go.moleculesai.app/plugin/gh-identity v0.0.0-20260509010445-788988195fce h1:ftm0ba0ukLlfqeFes+/jWnXH8XULXmRpMy3fOCZ83/U=
+go.moleculesai.app/plugin/gh-identity v0.0.0-20260509010445-788988195fce/go.mod h1:0aAqoDle2V7Cywso94MXdv1DH/HEe/0oZmcbqWYMK7g=
 go.mongodb.org/mongo-driver/v2 v2.5.0 h1:yXUhImUjjAInNcpTcAlPHiT7bIXhshCTL3jVBkF3xaE=
 go.mongodb.org/mongo-driver/v2 v2.5.0/go.mod h1:yOI9kBsufol30iFsl1slpdq1I0eHPzybRWdyYUs8K/0=
 go.opentelemetry.io/auto/sdk v1.2.1 h1:jXsnJ4Lmnqd11kwkBV2LgLoFMZKizbCi5fNZ/ipaZ64=

workspace-server/internal/handlers/mcp.go

@@ -28,6 +28,7 @@ import (
 	"database/sql"
 	"encoding/json"
 	"fmt"
+	"log"
 	"net/http"
 	"os"
 	"time"
@@ -326,7 +327,7 @@ func (h *MCPHandler) Call(c *gin.Context) {
 	if err := c.ShouldBindJSON(&req); err != nil {
 		c.JSON(http.StatusBadRequest, mcpResponse{
 			JSONRPC: "2.0",
-			Error:   &mcpRPCError{Code: -32700, Message: "parse error: " + err.Error()},
+			Error:   &mcpRPCError{Code: -32700, Message: "parse error"},
 		})
 		return
 	}
@@ -414,12 +415,16 @@ func (h *MCPHandler) dispatchRPC(ctx context.Context, workspaceID string, req mc
 			Arguments map[string]interface{} `json:"arguments"`
 		}
 		if err := json.Unmarshal(req.Params, &params); err != nil {
-			base.Error = &mcpRPCError{Code: -32602, Message: "invalid params: " + err.Error()}
+			base.Error = &mcpRPCError{Code: -32602, Message: "invalid parameters"}
 			return base
 		}
 		text, err := h.dispatch(ctx, workspaceID, params.Name, params.Arguments)
 		if err != nil {
-			base.Error = &mcpRPCError{Code: -32000, Message: err.Error()}
+			// Log full error server-side for forensics; return constant string
+			// to client per OFFSEC-001 / #259.  WorkspaceAuth required — caller
+			// already authenticated, so this is defence-in-depth.
+			log.Printf("mcp: tool call failed workspace=%s tool=%s: %v", workspaceID, params.Name, err)
+			base.Error = &mcpRPCError{Code: -32000, Message: "tool call failed"}
 			return base
 		}
 		base.Result = map[string]interface{}{

workspace-server/internal/handlers/mcp_test.go

@@ -1024,3 +1024,126 @@ func TestIsPrivateOrMetadataIP_PublicAllowed(t *testing.T) {
 		}
 	}
 }
+
+// TestMCPHandler_Call_MalformedJSON returns constant parse-error message.
+// Per OFFSEC-001 / #259: err.Error() must not leak struct field names or
+// JSON library internals in JSON-RPC error.message.
+func TestMCPHandler_Call_MalformedJSON_ReturnsConstantParseError(t *testing.T) {
+	h, _ := newMCPHandler(t)
+	w := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(w)
+	c.Params = gin.Params{{Key: "id", Value: "ws-1"}}
+	// Valid JSON-RPC 2.0 envelope but JSON body is malformed.
+	c.Request = httptest.NewRequest("POST", "/", bytes.NewBuffer([]byte("not valid json{][")))
+	c.Request.Header.Set("Content-Type", "application/json")
+
+	h.Call(c)
+
+	if w.Code != http.StatusBadRequest {
+		t.Fatalf("expected 400, got %d: %s", w.Code, w.Body.String())
+	}
+	var resp mcpResponse
+	if err := json.Unmarshal(w.Body.Bytes(), &resp); err != nil {
+		t.Fatalf("response is not valid JSON: %v", err)
+	}
+	if resp.Error == nil {
+		t.Fatal("expected JSON-RPC error, got nil")
+	}
+	// Message must be a constant — no err.Error() content.
+	if resp.Error.Message != "parse error" {
+		t.Errorf("error message should be constant 'parse error', got: %q", resp.Error.Message)
+	}
+	// Code must be -32700 (Parse error).
+	if resp.Error.Code != -32700 {
+		t.Errorf("error code should be -32700, got: %d", resp.Error.Code)
+	}
+}
+
+// TestMCPHandler_dispatchRPC_InvalidParams returns constant message.
+// Per OFFSEC-001 / #259: err.Error() from json.Unmarshal must not be
+// returned in JSON-RPC error.message.
+func TestMCPHandler_dispatchRPC_InvalidParams_ReturnsConstantMessage(t *testing.T) {
+	h, _ := newMCPHandler(t)
+
+	// Valid JSON-RPC but params is a string (not an object) — invalid for tools/call.
+	w := mcpPost(t, h, "ws-1", map[string]interface{}{
+		"jsonrpc": "2.0",
+		"id":      1,
+		"method":  "tools/call",
+		"params":  "not an object", // string instead of object — json.Unmarshal fails
+	})
+
+	var resp mcpResponse
+	if err := json.Unmarshal(w.Body.Bytes(), &resp); err != nil {
+		t.Fatalf("response is not valid JSON: %v", err)
+	}
+	if resp.Error == nil {
+		t.Fatal("expected JSON-RPC error, got nil")
+	}
+	// Message must be a constant — no JSON library error content.
+	if resp.Error.Message != "invalid parameters" {
+		t.Errorf("error message should be constant 'invalid parameters', got: %q", resp.Error.Message)
+	}
+	if resp.Error.Code != -32602 {
+		t.Errorf("error code should be -32602 (Invalid params), got: %d", resp.Error.Code)
+	}
+}
+
+// TestMCPHandler_dispatchRPC_UnknownTool returns constant tool-failed message.
+// Per OFFSEC-001 / #259: dispatch errors must not leak workspace IDs or
+// internal paths.  Note: this test exercises the dispatch path through
+// dispatchRPC since dispatch is package-private.
+func TestMCPHandler_dispatchRPC_UnknownTool_ReturnsConstantMessage(t *testing.T) {
+	h, _ := newMCPHandler(t)
+
+	// Valid params shape but tool name does not exist.
+	w := mcpPost(t, h, "ws-1", map[string]interface{}{
+		"jsonrpc": "2.0",
+		"id":      2,
+		"method":  "tools/call",
+		"params": map[string]interface{}{
+			"name":      "nonexistent_tool_xyz",
+			"arguments": map[string]interface{}{},
+		},
+	})
+
+	var resp mcpResponse
+	if err := json.Unmarshal(w.Body.Bytes(), &resp); err != nil {
+		t.Fatalf("response is not valid JSON: %v", err)
+	}
+	if resp.Error == nil {
+		t.Fatal("expected JSON-RPC error for unknown tool, got nil")
+	}
+	// Message must be a constant — no "unknown tool: nonexistent_tool_xyz" leak.
+	if resp.Error.Message != "tool call failed" {
+		t.Errorf("error message should be constant 'tool call failed', got: %q", resp.Error.Message)
+	}
+	if resp.Error.Code != -32000 {
+		t.Errorf("error code should be -32000 (Server error), got: %d", resp.Error.Code)
+	}
+}
+
+// TestMCPHandler_dispatchRPC_InvalidParams_NilParams covers the edge case
+// where params is present but not an object (e.g. an array). json.Unmarshal
+// into the params struct fails, and we assert the constant error message.
+func TestMCPHandler_dispatchRPC_InvalidParams_ArrayInsteadOfObject(t *testing.T) {
+	h, _ := newMCPHandler(t)
+
+	w := mcpPost(t, h, "ws-1", map[string]interface{}{
+		"jsonrpc": "2.0",
+		"id":      3,
+		"method":  "tools/call",
+		"params":  []interface{}{"one", "two"}, // array instead of object
+	})
+
+	var resp mcpResponse
+	if err := json.Unmarshal(w.Body.Bytes(), &resp); err != nil {
+		t.Fatalf("response is not valid JSON: %v", err)
+	}
+	if resp.Error == nil {
+		t.Fatal("expected JSON-RPC error, got nil")
+	}
+	if resp.Error.Message != "invalid parameters" {
+		t.Errorf("error message should be constant 'invalid parameters', got: %q", resp.Error.Message)
+	}
+}

workspace-server/internal/plugins/drift_sweeper.go

@@ -61,15 +61,26 @@ const DriftSweepInterval = 1 * time.Hour
 // that handles Gitea instances on high-latency links.
 const ResolveRefDeadline = 60 * time.Second
 
-// PluginResolver resolves plugin sources to installable directories.
-// Satisfied by *Registry (which wraps GithubResolver + LocalResolver).
+// PluginResolver is the registry-level abstraction the sweeper consumes:
+// pick a per-scheme SourceResolver for a parsed Source, and enumerate the
+// registered schemes so we can strip the prefix from a stored source_raw.
+//
+// Resolve returns the production SourceResolver from source.go (NOT another
+// PluginResolver) — that's the actual shape of *Registry.Resolve, and the
+// sweeper only needs the per-scheme resolver's identity, not its Fetch.
+//
 // Named PluginResolver (not SourceResolver) to avoid redeclaring the
-// SourceResolver interface defined in source.go (core#228 fix).
+// per-scheme SourceResolver interface defined in source.go (core#228 fix).
+// Satisfied by *Registry from source.go via Resolve + Schemes.
 type PluginResolver interface {
-	Resolve(source Source) (PluginResolver, error)
+	Resolve(source Source) (SourceResolver, error)
 	Schemes() []string
 }
 
+// Compile-time assertion: *Registry satisfies PluginResolver. Catches any
+// future drift in Registry.Resolve / Schemes signatures at build time.
+var _ PluginResolver = (*Registry)(nil)
+
 // StartPluginDriftSweeper runs the drift-detection loop until ctx is cancelled.
 // Pass a nil resolver to disable the sweeper (useful for harnesses or CP/SaaS
 // mode where git operations are unavailable).

workspace-server/internal/plugins/drift_sweeper_test.go

@@ -2,12 +2,14 @@ package plugins
 
 import (
 	"context"
-	"database/sql"
 	"errors"
 	"testing"
 )
 
-// stubResolver is a SourceResolver that always returns a stub github resolver.
+// stubResolver is a PluginResolver that always returns a stub github
+// resolver. *GithubResolver satisfies the production SourceResolver from
+// source.go via Scheme() + Fetch(); the sweeper only uses Schemes() and
+// Resolve(), so the returned resolver's Fetch is never invoked here.
 type stubResolver struct {
 	schemes []string
 }
@@ -156,8 +158,9 @@ func TestPluginUpdateQueueRow_Struct(t *testing.T) {
 	}
 }
 
-// TestSourceResolverInterface_StubResolver verifies that a stub resolver
-// satisfies the SourceResolver interface.
-func TestSourceResolverInterface_StubResolver(t *testing.T) {
-	var _ SourceResolver = (*stubResolver)(nil)
+// TestPluginResolverInterface_StubResolver verifies that a stub resolver
+// satisfies the PluginResolver interface (the sweeper-side abstraction
+// over *Registry — distinct from the per-scheme SourceResolver in source.go).
+func TestPluginResolverInterface_StubResolver(t *testing.T) {
+	var _ PluginResolver = (*stubResolver)(nil)
 }

workspace-server/internal/router/router.go

@@ -27,7 +27,15 @@ import (
 	"github.com/gin-gonic/gin"
 )
 
-func Setup(hub *ws.Hub, broadcaster *events.Broadcaster, prov *provisioner.Provisioner, platformURL, configsDir string, wh *handlers.WorkspaceHandler, channelMgr *channels.Manager, memBundle *memwiring.Bundle, pluginResolver plugins.SourceResolver) *gin.Engine {
+// Setup wires the gin router. pluginResolver is the registry-level resolver
+// (typically *plugins.Registry from main.go) reserved for future per-deploy
+// customisation — currently passed only to satisfy the call-site contract;
+// plgh (PluginsHandler) constructs its own internal registry with the
+// default github+local resolvers via NewPluginsHandler. The drift sweeper
+// (main.go) gets the same pluginResolver instance so it can share scheme
+// enumeration if a deployment registers extra schemes externally. A nil
+// pluginResolver is harmless: plgh still works with its built-in defaults.
+func Setup(hub *ws.Hub, broadcaster *events.Broadcaster, prov *provisioner.Provisioner, platformURL, configsDir string, wh *handlers.WorkspaceHandler, channelMgr *channels.Manager, memBundle *memwiring.Bundle, pluginResolver plugins.PluginResolver) *gin.Engine {
 	r := gin.Default()
 
 	// Issue #179 — trust no reverse-proxy headers. Without this call Gin's
@@ -499,6 +507,72 @@ func Setup(hub *ws.Hub, broadcaster *events.Broadcaster, prov *provisioner.Provi
 		r.POST("/admin/workspace-images/refresh", middleware.AdminAuth(db.DB), imgH.Refresh)
 	}
 
+	// dockerCli is shared across plugins, terminal, templates, and bundle
+	// handlers. Declared up-front (was at line ~594) because the plugins
+	// init block — moved here in 70f84823 to fix "undefined: plgh" — needs
+	// dockerCli at construction time (NewPluginsHandler signature). Moving
+	// only the plgh block left dockerCli used-before-declared. Same nil
+	// guard semantics: prov nil → dockerCli nil → handlers fall back to
+	// non-Docker paths or skip Docker-dependent routes.
+	var dockerCli *client.Client
+	if prov != nil {
+		dockerCli = prov.DockerClient()
+	}
+
+	// Plugins — plgh must be initialized before the drift handler that uses it.
+	// Moved here (core#248 fix) because the drift handler block (core#123) was
+	// registered before plgh was created, causing "undefined: plgh" on main.
+	pluginsDir := findPluginsDir(configsDir)
+	// Runtime lookup lets the plugins handler filter the registry to plugins
+	// that declare support for the workspace's runtime, without taking a
+	// direct DB dependency in the handler package.
+	runtimeLookup := func(workspaceID string) (string, error) {
+		var runtime string
+		err := db.DB.QueryRowContext(
+			context.Background(),
+			`SELECT COALESCE(runtime, 'langgraph') FROM workspaces WHERE id = $1`,
+			workspaceID,
+		).Scan(&runtime)
+		return runtime, err
+	}
+	// Instance-id lookup powers the SaaS dispatch in install/uninstall:
+	// when a workspace is on the EC2-per-workspace backend (instance_id
+	// non-NULL) and there's no local Docker container to exec into, the
+	// pipeline pushes the staged plugin tarball to that EC2 over EIC SSH.
+	// Empty result means the workspace lives on the local-Docker backend
+	// (or hasn't been provisioned yet) and the handler falls back to its
+	// original Docker path. Same pattern templates.go and terminal.go use.
+	instanceIDLookup := func(workspaceID string) (string, error) {
+		var instanceID string
+		err := db.DB.QueryRowContext(
+			context.Background(),
+			`SELECT COALESCE(instance_id, '') FROM workspaces WHERE id = $1`,
+			workspaceID,
+		).Scan(&instanceID)
+		return instanceID, err
+	}
+	// plgh constructs its own internal registry (github + local) inside
+	// NewPluginsHandler. The pluginResolver param is the SHARED registry the
+	// drift sweeper consumes (main.go); we don't graft it onto plgh because
+	// plgh's WithSourceResolver expects a per-scheme SourceResolver, not a
+	// PluginResolver/registry. Cross-wiring those types was the original
+	// "*Registry doesn't implement SourceResolver" build break (core#228).
+	// Use of pluginResolver here is intentionally read-side only.
+	_ = pluginResolver
+	plgh := handlers.NewPluginsHandler(pluginsDir, dockerCli, wh.RestartByID).
+		WithRuntimeLookup(runtimeLookup).
+		WithInstanceIDLookup(instanceIDLookup)
+	r.GET("/plugins", plgh.ListRegistry)
+	r.GET("/plugins/sources", plgh.ListSources)
+	wsAuth.GET("/plugins", plgh.ListInstalled)
+	wsAuth.GET("/plugins/available", plgh.ListAvailableForWorkspace)
+	wsAuth.GET("/plugins/compatibility", plgh.CheckRuntimeCompatibility)
+	wsAuth.POST("/plugins", plgh.Install)
+	wsAuth.DELETE("/plugins/:name", plgh.Uninstall)
+	// Phase 30.3 — stream plugin as tar.gz so remote agents can pull +
+	// unpack locally instead of going through Docker exec.
+	wsAuth.GET("/plugins/:name/download", plgh.Download)
+
 	// Admin — plugin version-subscription drift queue (core#123).
 	// List pending drift entries and apply approved updates.
 	{
@@ -537,11 +611,7 @@ func Setup(hub *ws.Hub, broadcaster *events.Broadcaster, prov *provisioner.Provi
 		wsAuth.GET("/github-installation-token", ghTokH.GetInstallationToken)
 	}
 
-	// Terminal — shares Docker client with provisioner
-	var dockerCli *client.Client
-	if prov != nil {
-		dockerCli = prov.DockerClient()
-	}
+	// Terminal — shares Docker client with provisioner (declared above).
 	th := handlers.NewTerminalHandler(dockerCli)
 	wsAuth.GET("/terminal", th.HandleConnect)
 	wsAuth.GET("/terminal/diagnose", th.HandleDiagnose)
@@ -595,57 +665,6 @@ func Setup(hub *ws.Hub, broadcaster *events.Broadcaster, prov *provisioner.Provi
 	wsAuth.GET("/pending-uploads/:file_id/content", puh.GetContent)
 	wsAuth.POST("/pending-uploads/:file_id/ack", puh.Ack)
 
-	// Plugins
-	pluginsDir := findPluginsDir(configsDir)
-	// Runtime lookup lets the plugins handler filter the registry to plugins
-	// that declare support for the workspace's runtime, without taking a
-	// direct DB dependency in the handler package.
-	runtimeLookup := func(workspaceID string) (string, error) {
-		var runtime string
-		err := db.DB.QueryRowContext(
-			context.Background(),
-			`SELECT COALESCE(runtime, 'langgraph') FROM workspaces WHERE id = $1`,
-			workspaceID,
-		).Scan(&runtime)
-		return runtime, err
-	}
-	// Instance-id lookup powers the SaaS dispatch in install/uninstall:
-	// when a workspace is on the EC2-per-workspace backend (instance_id
-	// non-NULL) and there's no local Docker container to exec into, the
-	// pipeline pushes the staged plugin tarball to that EC2 over EIC SSH.
-	// Empty result means the workspace lives on the local-Docker backend
-	// (or hasn't been provisioned yet) and the handler falls back to its
-	// original Docker path. Same pattern templates.go and terminal.go use.
-	instanceIDLookup := func(workspaceID string) (string, error) {
-		var instanceID string
-		err := db.DB.QueryRowContext(
-			context.Background(),
-			`SELECT COALESCE(instance_id, '') FROM workspaces WHERE id = $1`,
-			workspaceID,
-		).Scan(&instanceID)
-		return instanceID, err
-	}
-	// pluginResolver: when provided (normal production), use it for plgh so
-	// the drift sweeper (which also gets the same resolver in main.go) uses
-	// identical resolver state. When nil (test / backward compat), let
-	// NewPluginsHandler create its own default registry.
-	plgh := handlers.NewPluginsHandler(pluginsDir, dockerCli, wh.RestartByID).
-		WithRuntimeLookup(runtimeLookup).
-		WithInstanceIDLookup(instanceIDLookup)
-	if pluginResolver != nil {
-		plgh = plgh.WithSourceResolver(pluginResolver)
-	}
-	r.GET("/plugins", plgh.ListRegistry)
-	r.GET("/plugins/sources", plgh.ListSources)
-	wsAuth.GET("/plugins", plgh.ListInstalled)
-	wsAuth.GET("/plugins/available", plgh.ListAvailableForWorkspace)
-	wsAuth.GET("/plugins/compatibility", plgh.CheckRuntimeCompatibility)
-	wsAuth.POST("/plugins", plgh.Install)
-	wsAuth.DELETE("/plugins/:name", plgh.Uninstall)
-	// Phase 30.3 — stream plugin as tar.gz so remote agents can pull +
-	// unpack locally instead of going through Docker exec.
-	wsAuth.GET("/plugins/:name/download", plgh.Download)
-
 	// Bundles — #164 + #165: both gated behind AdminAuth.
 	//   POST /bundles/import — CRITICAL: anon creation of arbitrary workspaces
 	//                          with user-supplied config (system prompts,

workspace/a2a_response.py

@@ -179,6 +179,23 @@ 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

@@ -66,10 +66,23 @@ async def delegate_task(workspace_id: str, task: str) -> str:
             )
             data = a2a_resp.json()
             if "result" in data:
-                parts = data["result"].get("parts", [])
-                return parts[0].get("text", "(no text)") if parts else str(data["result"])
+                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)"
             elif "error" in data:
-                return f"Error: {data['error'].get('message', str(data['error']))}"
+                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 str(data)
         except Exception as e:
             return f"Error sending A2A message: {e}"