feat(hyperguild): mode client-local writes routing headers

Plan 6 is now deployed; replace the _routing_pending placeholder in the
routing MCP entry with a real headers block carrying X-Hyperguild-Mode:
client-local. The pod treats absent or unknown values as client-local,
so this is forward-compat for future modes.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

cmd/hyperguild/README.md

@@ -115,9 +115,10 @@ Flags:
 Modes:
 
 - **cloud** — brain MCP only. Claude Code with no routing.
-- **client-local** — brain + routing placeholder. The routing entry's
-  URL points at `koala:30310/mcp`; a `_routing_pending` field marks it
-  as awaiting Plan 6 of the hyperguild migration.
+- **client-local** — brain + routing pod. The `routing` entry points at
+  `koala:30310/mcp` (the routing pod, deployed in Plan 6). The
+  `X-Hyperguild-Mode: client-local` header is forward-compat for future
+  modes; the pod treats absent or unknown values as `client-local`.
 - **sovereign** — brain only, with a `_mode_note` explaining that this
   mode primarily uses Crush + LiteLLM and the `.mcp.json` is a Claude
   Code fallback for emergency offline use.

cmd/hyperguild/mode.go

@@ -78,9 +78,11 @@ func modeClientLocal(brainURL string) map[string]any {
 				"description": "Brain MCP — knowledge query, write, ingestion, session log",
 			},
 			"routing": map[string]any{
-				"url":              "http://koala:30310/mcp",
-				"description":      "Mode 2 routing pod — routes skill calls to LiteLLM/local",
-				"_routing_pending": "Plan 6 — routing pod not deployed yet; this URL is a placeholder",
+				"url":         "http://koala:30310/mcp",
+				"description": "Mode 2 routing pod — routes skill calls to LiteLLM/local",
+				"headers": map[string]any{
+					"X-Hyperguild-Mode": "client-local",
+				},
 			},
 		},
 	}

cmd/hyperguild/mode_test.go

@@ -39,7 +39,7 @@ func TestRunMode_Cloud_Default(t *testing.T) {
 	assert.NotContains(t, got, "_mode_note")
 }
 
-func TestRunMode_ClientLocal_HasRoutingPlaceholder(t *testing.T) {
+func TestRunMode_ClientLocal_HasRoutingEntry(t *testing.T) {
 	dir := t.TempDir()
 	outPath := filepath.Join(dir, ".mcp.json")
 	t.Setenv("BRAIN_URL", "http://koala:30330")
@@ -54,7 +54,32 @@ func TestRunMode_ClientLocal_HasRoutingPlaceholder(t *testing.T) {
 	require.Contains(t, servers, "routing")
 
 	routing := servers["routing"].(map[string]any)
-	assert.Contains(t, routing, "_routing_pending")
+	assert.NotContains(t, routing, "_routing_pending", "placeholder should be removed once Plan 6 ships")
+
+	headers, ok := routing["headers"].(map[string]any)
+	require.True(t, ok, "routing entry should have headers block")
+	assert.Equal(t, "client-local", headers["X-Hyperguild-Mode"])
+}
+
+func TestModeClientLocalHasRoutingHeader(t *testing.T) {
+	tmp := t.TempDir() + "/mcp.json"
+	out := &bytes.Buffer{}
+	stderr := &bytes.Buffer{}
+	require.NoError(t, runMode(context.Background(), []string{"client-local", "--out", tmp}, nil, out, stderr))
+
+	body, err := os.ReadFile(tmp)
+	require.NoError(t, err)
+	var doc map[string]any
+	require.NoError(t, json.Unmarshal(body, &doc))
+
+	servers := doc["mcpServers"].(map[string]any)
+	routing := servers["routing"].(map[string]any)
+	assert.Equal(t, "http://koala:30310/mcp", routing["url"])
+	assert.NotContains(t, routing, "_routing_pending", "placeholder should be removed once Plan 6 ships")
+
+	headers, ok := routing["headers"].(map[string]any)
+	require.True(t, ok, "routing entry should have headers block")
+	assert.Equal(t, "client-local", headers["X-Hyperguild-Mode"])
 }
 
 func TestRunMode_Sovereign_HasModeNote(t *testing.T) {