diff --git a/apps/server/src/provider/Layers/ClaudeAdapter.test.ts b/apps/server/src/provider/Layers/ClaudeAdapter.test.ts
index 7917b8360946..5344481385d1 100644
--- a/apps/server/src/provider/Layers/ClaudeAdapter.test.ts
+++ b/apps/server/src/provider/Layers/ClaudeAdapter.test.ts
@@ -3945,8 +3945,8 @@ describe("ClaudeAdapterLive", () => {
         attachments: [],
       });
 
-      // No explicit model/effort on the launch input: the task inherits the
-      // session's selection.
+      // No explicit model/effort on the launch input: the model starts from the
+      // session's selection, and effort stays unknown.
       harness.query.emit({
         type: "system",
         subtype: "task_started",
@@ -3984,13 +3984,13 @@ describe("ClaudeAdapterLive", () => {
       assert.equal(started?.type, "task.started");
       if (started?.type === "task.started") {
         assert.equal(started.payload.model, SYNTHETIC_CLAUDE_CAPABLE_MODEL);
-        assert.equal(started.payload.effort, "max");
+        assert.equal(started.payload.effort, undefined);
       }
       const progress = taskEvents[1];
       assert.equal(progress?.type, "task.progress");
       if (progress?.type === "task.progress") {
         assert.equal(progress.payload.model, SYNTHETIC_SUBAGENT_MODEL);
-        assert.equal(progress.payload.effort, "max");
+        assert.equal(progress.payload.effort, undefined);
       }
     }).pipe(
       Effect.provideService(Random.Random, makeDeterministicRandomService()),
@@ -4063,7 +4063,7 @@ describe("ClaudeAdapterLive", () => {
       assert.equal(started?.type, "task.started");
       if (started?.type === "task.started") {
         assert.equal(started.payload.model, SYNTHETIC_SUBAGENT_MODEL);
-        assert.equal(started.payload.effort, "max");
+        assert.equal(started.payload.effort, undefined);
       }
       const progress = taskEvents[1];
       assert.equal(progress?.type, "task.progress");
@@ -4076,6 +4076,84 @@ describe("ClaudeAdapterLive", () => {
     );
   });
 
+  it.effect("a subagent resumed by SendMessage keeps its model and effort", () => {
+    const harness = makeHarness();
+    return Effect.gen(function* () {
+      const adapter = yield* ClaudeAdapter;
+
+      const startedFiber = yield* adapter.streamEvents.pipe(
+        Stream.filter((event) => event.type === "task.started"),
+        Stream.take(2),
+        Stream.runCollect,
+        Effect.forkChild,
+      );
+
+      const session = yield* adapter.startSession({
+        threadId: THREAD_ID,
+        provider: ProviderDriverKind.make("claudeAgent"),
+        modelSelection: createModelSelection(
+          ProviderInstanceId.make("claudeAgent"),
+          SYNTHETIC_CLAUDE_CAPABLE_MODEL,
+          [{ id: "effort", value: "max" }],
+        ),
+        runtimeMode: "full-access",
+      });
+      yield* adapter.sendTurn({
+        threadId: session.threadId,
+        input: "spawn an agent",
+        attachments: [],
+      });
+
+      const toolUse = (index: number, id: string, name: string, input: object) =>
+        harness.query.emit({
+          type: "stream_event",
+          session_id: "sdk-session",
+          uuid: `stream-${id}`,
+          parent_tool_use_id: null,
+          event: {
+            type: "content_block_start",
+            index,
+            content_block: { type: "tool_use", id, name, input },
+          },
+        } as unknown as SDKMessage);
+      const taskStarted = (toolUseId: string) =>
+        harness.query.emit({
+          type: "system",
+          subtype: "task_started",
+          task_id: "task-resumed",
+          description: "Agent R",
+          task_type: "local_agent",
+          tool_use_id: toolUseId,
+          uuid: `task-resumed-${toolUseId}`,
+          session_id: "sdk-session",
+        } as unknown as SDKMessage);
+
+      toolUse(0, "toolu_agent_r", "Agent", { description: "Agent R", effort: "high" });
+      taskStarted("toolu_agent_r");
+      harness.query.emit({
+        type: "assistant",
+        parent_tool_use_id: "toolu_agent_r",
+        message: { model: SYNTHETIC_SUBAGENT_MODEL, content: [] },
+        uuid: "resumed-snapshot-uuid",
+        session_id: "sdk-session",
+      } as unknown as SDKMessage);
+      // Reviving a finished agent re-registers the same task under the
+      // SendMessage call, whose input names neither model nor effort.
+      toolUse(1, "toolu_send_r", "SendMessage", { to: "task-resumed", message: "continue" });
+      taskStarted("toolu_send_r");
+
+      const resumed = Array.from(yield* Fiber.join(startedFiber))[1];
+      assert.equal(resumed?.type, "task.started");
+      if (resumed?.type === "task.started") {
+        assert.equal(resumed.payload.model, SYNTHETIC_SUBAGENT_MODEL);
+        assert.equal(resumed.payload.effort, "high");
+      }
+    }).pipe(
+      Effect.provideService(Random.Random, makeDeterministicRandomService()),
+      Effect.provide(harness.layer),
+    );
+  });
+
   it.effect("closes the session when the Claude stream aborts after a turn starts", () => {
     const harness = makeHarness();
     return Effect.gen(function* () {
diff --git a/apps/server/src/provider/Layers/ClaudeAdapter.ts b/apps/server/src/provider/Layers/ClaudeAdapter.ts
index d50b3cbb9248..0ee30f8c5dda 100644
--- a/apps/server/src/provider/Layers/ClaudeAdapter.ts
+++ b/apps/server/src/provider/Layers/ClaudeAdapter.ts
@@ -417,9 +417,6 @@ interface ClaudeSessionContext {
   readonly startedAt: string;
   readonly basePermissionMode: PermissionMode | undefined;
   currentApiModelId: string | undefined;
-  /** Effective effort for the session's turns; subagents without an explicit
-   * effort override inherit this. */
-  currentEffort: string | undefined;
   resumeSessionId: string | undefined;
   readonly pendingApprovals: Map<ApprovalRequestId, PendingApproval>;
   readonly pendingUserInputs: Map<ApprovalRequestId, PendingUserInput>;
@@ -3720,28 +3717,33 @@ export const makeClaudeAdapter = Effect.fn("makeClaudeAdapter")(function* (
         ) {
           context.turnState.hasSubagents = true;
         }
-        // Model/effort: the Agent tool's input carries explicit overrides;
-        // absent ones inherit the session's selection (SDK behavior).
-        // Subagent assistant snapshots refine model with the authoritative API
-        // id: one that already arrived is buffered and outranks the seed here,
-        // later ones refine the record in place. AgentInput.effort may be a
-        // named level or an integer.
+        // Model/effort: the Agent tool's input carries explicit overrides.
+        // A resumed agent re-registers under the same task_id, launched by a
+        // SendMessage call that carries neither, so it keeps what is already
+        // known. A fresh agent's model falls back to the session's, and
+        // subagent assistant snapshots refine it with the authoritative API id:
+        // one that already arrived is buffered and outranks the seed here,
+        // later ones refine the record in place. Effort has no such source (an
+        // agent definition may set its own), so it is only reported when
+        // explicit. AgentInput.effort may be a named level or an integer.
         const launchInput = launchingTool?.input;
         const toolUseId = message.tool_use_id;
         const bufferedModel = toolUseId ? context.pendingTaskModels.get(toolUseId) : undefined;
         if (toolUseId) {
           context.pendingTaskModels.delete(toolUseId);
         }
+        const known = context.taskAgents.get(message.task_id);
         const model =
           bufferedModel ??
           trimmedString(launchInput?.model) ??
+          known?.model ??
           trimmedString(context.session.model ?? undefined);
         const rawLaunchEffort = launchInput?.effort;
         const effort =
           trimmedString(rawLaunchEffort) ??
           (typeof rawLaunchEffort === "number" && Number.isFinite(rawLaunchEffort)
             ? String(rawLaunchEffort)
-            : context.currentEffort);
+            : known?.effort);
         // Remember the agent identity so every later task.* payload for this
         // taskId is self-describing (identity must survive activity retention).
         context.taskAgents.set(message.task_id, {
@@ -3752,7 +3754,7 @@ export const makeClaudeAdapter = Effect.fn("makeClaudeAdapter")(function* (
           taskType: message.task_type,
           workflowName: message.workflow_name,
           skipTranscript: message.skip_transcript === true,
-          runHandles: context.taskAgents.get(message.task_id)?.runHandles,
+          runHandles: known?.runHandles,
           owningAgentId,
           model,
           effort,
@@ -5036,7 +5038,6 @@ export const makeClaudeAdapter = Effect.fn("makeClaudeAdapter")(function* (
         startedAt,
         basePermissionMode: permissionMode,
         currentApiModelId: apiModelId,
-        currentEffort: effectiveEffort ?? undefined,
         resumeSessionId: sessionId,
         pendingApprovals,
         pendingUserInputs,
@@ -5172,14 +5173,6 @@ export const makeClaudeAdapter = Effect.fn("makeClaudeAdapter")(function* (
         ...context.session,
         model: modelSelection.model,
       };
-      const turnEffort = resolveClaudeCatalogEffort(
-        modelCatalog,
-        modelSelection.model,
-        getModelSelectionStringOptionValue(modelSelection, "effort"),
-      );
-      context.currentEffort =
-        getEffectiveClaudeAgentEffort(modelCatalog, turnEffort ?? null, modelSelection.model) ??
-        undefined;
     }
 
     // Apply interaction mode by switching the SDK's permission mode.