diff --git a/internal/routing/snapshot_test.go b/internal/routing/snapshot_test.go
new file mode 100644
index 0000000..c79f7df
--- /dev/null
+++ b/internal/routing/snapshot_test.go
@@ -0,0 +1,80 @@
+package routing_test
+
+import (
+	"context"
+	"encoding/json"
+	"os"
+	"sort"
+	"testing"
+
+	"github.com/mathiasbq/supervisor/internal/registry"
+	"github.com/mathiasbq/supervisor/internal/skills/debug"
+	"github.com/mathiasbq/supervisor/internal/skills/retrospective"
+	"github.com/mathiasbq/supervisor/internal/skills/review"
+	"github.com/mathiasbq/supervisor/internal/skills/trainer"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// TestToolsListMatchesSupervisorSnapshot pins the four routed skills' tool
+// definitions to the supervisor's current advertisement. A deliberate schema
+// change must be reflected here by updating testdata/tools_list.snapshot.json.
+func TestToolsListMatchesSupervisorSnapshot(t *testing.T) {
+	complete := func(_ context.Context, _, _, _ string) (string, int64, error) {
+		return "", 0, nil
+	}
+
+	reg := registry.New()
+	reg.Register(review.New(review.Config{
+		SkillPrompt:  "stub",
+		DefaultModel: "stub",
+		CompleteFunc: complete,
+	}))
+	reg.Register(debug.New(debug.Config{
+		SkillPrompt:  "stub",
+		DefaultModel: "stub",
+		CompleteFunc: complete,
+	}))
+	reg.Register(retrospective.New(retrospective.Config{
+		SkillPrompt:  "stub",
+		DefaultModel: "stub",
+		CompleteFunc: complete,
+	}))
+	reg.Register(trainer.New(trainer.Config{
+		ReaderPrompt: "stub",
+		WriterPrompt: "stub",
+		DefaultModel: "stub",
+		CompleteFunc: complete,
+	}))
+
+	wanted := map[string]bool{
+		"review":        true,
+		"debug":         true,
+		"retrospective": true,
+		"trainer":       true,
+	}
+	var routed []registry.ToolDef
+	for _, td := range reg.Tools() {
+		if wanted[td.Name] {
+			routed = append(routed, td)
+		}
+	}
+	sort.Slice(routed, func(i, j int) bool { return routed[i].Name < routed[j].Name })
+
+	got, err := json.MarshalIndent(routed, "", "  ")
+	require.NoError(t, err)
+
+	want, err := os.ReadFile("testdata/tools_list.snapshot.json")
+	require.NoError(t, err)
+
+	// Normalize both via re-encode so whitespace differences don't dominate.
+	var gotV, wantV any
+	require.NoError(t, json.Unmarshal(got, &gotV))
+	require.NoError(t, json.Unmarshal(want, &wantV))
+
+	gotN, _ := json.MarshalIndent(gotV, "", "  ")
+	wantN, _ := json.MarshalIndent(wantV, "", "  ")
+
+	assert.Equal(t, string(wantN), string(gotN),
+		"tool advertisement drifted from supervisor snapshot — update testdata/tools_list.snapshot.json deliberately if the schema change is intentional")
+}
diff --git a/internal/routing/testdata/tools_list.snapshot.json b/internal/routing/testdata/tools_list.snapshot.json
new file mode 100644
index 0000000..859602e
--- /dev/null
+++ b/internal/routing/testdata/tools_list.snapshot.json
@@ -0,0 +1,97 @@
+[
+  {
+    "name": "debug",
+    "description": "Consult a local model to analyse an error and return hypotheses ordered by likelihood, each with a concrete verification step.",
+    "inputSchema": {
+      "properties": {
+        "context": {
+          "type": "string"
+        },
+        "error": {
+          "type": "string"
+        },
+        "model": {
+          "type": "string"
+        },
+        "project_root": {
+          "type": "string"
+        },
+        "session_id": {
+          "type": "string"
+        }
+      },
+      "required": [
+        "project_root",
+        "error"
+      ],
+      "type": "object"
+    }
+  },
+  {
+    "name": "retrospective",
+    "description": "Consult a local model to analyse a completed session and identify what is novel or worth preserving as organizational knowledge.",
+    "inputSchema": {
+      "type": "object",
+      "required": [
+        "session_id"
+      ],
+      "properties": {
+        "session_id": {
+          "type": "string"
+        },
+        "model": {
+          "type": "string"
+        }
+      }
+    }
+  },
+  {
+    "name": "review",
+    "description": "Consult a local model for a structured code review of the specified files. Returns findings with severity levels.",
+    "inputSchema": {
+      "properties": {
+        "context": {
+          "type": "string"
+        },
+        "files": {
+          "items": {
+            "type": "string"
+          },
+          "type": "array"
+        },
+        "model": {
+          "type": "string"
+        },
+        "project_root": {
+          "type": "string"
+        },
+        "session_id": {
+          "type": "string"
+        }
+      },
+      "required": [
+        "project_root",
+        "files"
+      ],
+      "type": "object"
+    }
+  },
+  {
+    "name": "trainer",
+    "description": "Consult a local model to identify learning moments from a session log and suggest knowledge to preserve in the brain.",
+    "inputSchema": {
+      "properties": {
+        "model": {
+          "type": "string"
+        },
+        "session_id": {
+          "type": "string"
+        }
+      },
+      "required": [
+        "session_id"
+      ],
+      "type": "object"
+    }
+  }
+]