diff --git a/apps/server/src/provider/Layers/DroidAdapter.ts b/apps/server/src/provider/Layers/DroidAdapter.ts
index 04f8e7ba..ca3c4c88 100644
--- a/apps/server/src/provider/Layers/DroidAdapter.ts
+++ b/apps/server/src/provider/Layers/DroidAdapter.ts
@@ -2052,7 +2052,6 @@ export function makeDroidAdapter(
             cwd,
             clientName: "Scient Model Discovery",
           });
-          yield* runtime.start();
           const result = yield* discoverDroidAcpModels(runtime);
           const commands = yield* runtime.getAvailableCommands;
           setDroidDiscoveryCacheEntry(commandDiscoveryCache, cacheKey, {
diff --git a/apps/server/src/provider/acp/DroidAcpSupport.test.ts b/apps/server/src/provider/acp/DroidAcpSupport.test.ts
index 663610f5..3c3a6687 100644
--- a/apps/server/src/provider/acp/DroidAcpSupport.test.ts
+++ b/apps/server/src/provider/acp/DroidAcpSupport.test.ts
@@ -246,7 +246,9 @@ describe("applyDroidAcpInteractionMode", () => {
 });
 
 describe("discoverDroidAcpModels", () => {
-  it("reads each model's reasoning choices from session config options", async () => {
+  it("starts the session before reading each model's reasoning choices", async () => {
+    let startCalls = 0;
+    let started = false;
     let currentModel = "model-a";
     const configOptions = (): ReadonlyArray<EffectAcpSchema.SessionConfigOption> => [
       {
@@ -283,7 +285,22 @@ describe("discoverDroidAcpModels", () => {
       },
     ];
     const runtime = {
-      getConfigOptions: Effect.sync(configOptions),
+      start: () =>
+        Effect.sync(() => {
+          startCalls += 1;
+          started = true;
+          return {
+            sessionId: "droid-model-discovery-test",
+            initializeResult: { protocolVersion: 1 },
+            sessionSetupResult: {
+              sessionId: "droid-model-discovery-test",
+              configOptions: configOptions(),
+            },
+            modelConfigId: "model",
+            sessionSetupMethod: "new" as const,
+          };
+        }),
+      getConfigOptions: Effect.sync(() => (started ? configOptions() : [])),
       setConfigOption: (configId: string, value: string | boolean) => {
         if (configId === "model") {
           currentModel = String(value);
@@ -293,6 +310,7 @@ describe("discoverDroidAcpModels", () => {
     };
 
     const result = await Effect.runPromise(discoverDroidAcpModels(runtime));
+    expect(startCalls).toBe(1);
     expect(result.models).toEqual([
       expect.objectContaining({
         slug: "model-a",
diff --git a/apps/server/src/provider/acp/DroidAcpSupport.ts b/apps/server/src/provider/acp/DroidAcpSupport.ts
index 592386e1..e0bdb473 100644
--- a/apps/server/src/provider/acp/DroidAcpSupport.ts
+++ b/apps/server/src/provider/acp/DroidAcpSupport.ts
@@ -400,13 +400,18 @@ function droidModelDescriptor(
 }
 
 /**
- * Reads the model catalog from ACP and reselects each model so Droid returns that
- * model's current reasoning choices. Discovery runs in a disposable session.
+ * Starts the disposable ACP session, reads its model catalog, and reselects each
+ * model so Droid returns that model's current reasoning choices.
+ *
+ * Owning startup here keeps every discovery caller on the same lifecycle path;
+ * reading configuration before `session/new` completes always produces an empty
+ * inventory.
  */
 export function discoverDroidAcpModels(
-  runtime: Pick<AcpSessionRuntimeShape, "getConfigOptions" | "setConfigOption">,
+  runtime: Pick<AcpSessionRuntimeShape, "start" | "getConfigOptions" | "setConfigOption">,
 ): Effect.Effect<ProviderListModelsResult, EffectAcpErrors.AcpError> {
   return Effect.gen(function* () {
+    yield* runtime.start();
     const initialOptions = yield* runtime.getConfigOptions;
     const modelConfig = findDroidSelectConfig(initialOptions, {
       id: DROID_MODEL_CONFIG_ID,