diff --git a/packages/server/src/server/agent/providers/claude-agent.env.test.ts b/packages/server/src/server/agent/providers/claude-agent.env.test.ts
index c3a1c9a45..26b0e7f83 100644
--- a/packages/server/src/server/agent/providers/claude-agent.env.test.ts
+++ b/packages/server/src/server/agent/providers/claude-agent.env.test.ts
@@ -66,6 +66,7 @@ describe("Claude SDK env", () => {
     const client = new ClaudeAgentClient({
       logger: createTestLogger(),
       queryFactory,
+      resolveBinary: async () => "/test/claude/bin",
     });
     const session = await client.createSession(
       {
@@ -123,6 +124,7 @@ describe("Claude SDK env", () => {
     const client = new ClaudeAgentClient({
       logger: createTestLogger(),
       queryFactory,
+      resolveBinary: async () => "/test/claude/bin",
     });
     const session = await client.resumeSession(
       {
diff --git a/packages/server/src/server/agent/providers/claude-agent.interrupt-restart-regression.test.ts b/packages/server/src/server/agent/providers/claude-agent.interrupt-restart-regression.test.ts
index 4ad86767a..bcf4c2e91 100644
--- a/packages/server/src/server/agent/providers/claude-agent.interrupt-restart-regression.test.ts
+++ b/packages/server/src/server/agent/providers/claude-agent.interrupt-restart-regression.test.ts
@@ -261,7 +261,7 @@ test("interrupt only calls query.interrupt and leaves the query open", async ()
     return scriptedQuery;
   });
 
-  const client = new ClaudeAgentClient({ logger });
+  const client = new ClaudeAgentClient({ logger, resolveBinary: async () => "/test/claude/bin" });
   const session = await client.createSession({
     provider: "claude",
     cwd: process.cwd(),
@@ -311,7 +311,7 @@ test("reuses the existing query after interrupt before starting the next prompt"
     return scriptedQuery;
   });
 
-  const client = new ClaudeAgentClient({ logger });
+  const client = new ClaudeAgentClient({ logger, resolveBinary: async () => "/test/claude/bin" });
   const session = await client.createSession({
     provider: "claude",
     cwd: process.cwd(),
@@ -361,7 +361,7 @@ test("emits an assistant system notice when Claude changes session id mid-turn",
     return queryRef;
   });
 
-  const client = new ClaudeAgentClient({ logger });
+  const client = new ClaudeAgentClient({ logger, resolveBinary: async () => "/test/claude/bin" });
   const session = await client.createSession({
     provider: "claude",
     cwd: process.cwd(),
@@ -455,7 +455,7 @@ test("recovers when the query pump sees a single interrupt abort before the next
     return scriptedQuery;
   });
 
-  const client = new ClaudeAgentClient({ logger });
+  const client = new ClaudeAgentClient({ logger, resolveBinary: async () => "/test/claude/bin" });
   const session = await client.createSession({
     provider: "claude",
     cwd: process.cwd(),
@@ -488,7 +488,7 @@ test("stale abort result after replacement start does not poison the new foregro
     return queryRef;
   });
 
-  const client = new ClaudeAgentClient({ logger });
+  const client = new ClaudeAgentClient({ logger, resolveBinary: async () => "/test/claude/bin" });
   const session = await client.createSession({
     provider: "claude",
     cwd: process.cwd(),
@@ -564,7 +564,7 @@ test("creates an autonomous live turn when assistant output arrives without a fo
     return queryRef;
   });
 
-  const client = new ClaudeAgentClient({ logger });
+  const client = new ClaudeAgentClient({ logger, resolveBinary: async () => "/test/claude/bin" });
   const session = await client.createSession({
     provider: "claude",
     cwd: process.cwd(),
@@ -634,7 +634,7 @@ test("auto-completes an open autonomous turn when a foreground prompt starts", a
     return queryRef;
   });
 
-  const client = new ClaudeAgentClient({ logger });
+  const client = new ClaudeAgentClient({ logger, resolveBinary: async () => "/test/claude/bin" });
   const session = await client.createSession({
     provider: "claude",
     cwd: process.cwd(),
diff --git a/packages/server/src/server/agent/providers/claude-agent.redesign.test.ts b/packages/server/src/server/agent/providers/claude-agent.redesign.test.ts
index 12b6cfca2..5befae014 100644
--- a/packages/server/src/server/agent/providers/claude-agent.redesign.test.ts
+++ b/packages/server/src/server/agent/providers/claude-agent.redesign.test.ts
@@ -66,6 +66,7 @@ async function createSession() {
   const client = new ClaudeAgentClient({
     logger: createTestLogger(),
     queryFactory: sdkQueryFactory,
+    resolveBinary: async () => "/test/claude/bin",
   });
   return client.createSession({
     provider: "claude",
@@ -77,6 +78,7 @@ function createSessionWithLogger(logger: Logger) {
   const client = new ClaudeAgentClient({
     logger,
     queryFactory: sdkQueryFactory,
+    resolveBinary: async () => "/test/claude/bin",
   });
   return client.createSession({
     provider: "claude",
@@ -223,6 +225,7 @@ test("logs redacted query summary and never leaks sentinel secrets", async () =>
         PASEO_RUNTIME_SENTINEL_SECRET: runtimeSecret,
       },
     },
+    resolveBinary: async () => "/test/claude/bin",
   });
   const session = await client.createSession({
     provider: "claude",
@@ -797,6 +800,7 @@ test("captures Claude stderr in the turn failure diagnostic when stderr arrives
   const client = new ClaudeAgentClient({
     logger: loggerSpy.logger,
     queryFactory: sdkQueryFactory,
+    resolveBinary: async () => "/test/claude/bin",
   });
   const session = await client.createSession({
     provider: "claude",
diff --git a/packages/server/src/server/agent/providers/claude-agent.spawn.test.ts b/packages/server/src/server/agent/providers/claude-agent.spawn.test.ts
index d57f07402..5382d30a5 100644
--- a/packages/server/src/server/agent/providers/claude-agent.spawn.test.ts
+++ b/packages/server/src/server/agent/providers/claude-agent.spawn.test.ts
@@ -77,6 +77,7 @@ describe("Claude spawn override", () => {
     const client = new ClaudeAgentClient({
       logger: createTestLogger(),
       queryFactory,
+      resolveBinary: async () => "/test/claude/bin",
     });
     const session = await client.createSession({
       provider: "claude",
diff --git a/packages/server/src/server/agent/providers/claude-agent.sub-agent-sidechain.test.ts b/packages/server/src/server/agent/providers/claude-agent.sub-agent-sidechain.test.ts
index 9b7744a22..9f340de09 100644
--- a/packages/server/src/server/agent/providers/claude-agent.sub-agent-sidechain.test.ts
+++ b/packages/server/src/server/agent/providers/claude-agent.sub-agent-sidechain.test.ts
@@ -251,7 +251,10 @@ describe("ClaudeAgentSession sub-agent sidechain updates", () => {
   });
 
   test("accumulates lightweight sub_agent detail and preserves callId lifecycle collapse", async () => {
-    const session = await new ClaudeAgentClient({ logger }).createSession({
+    const session = await new ClaudeAgentClient({
+      logger,
+      resolveBinary: async () => "/test/claude/bin",
+    }).createSession({
       provider: "claude",
       cwd: process.cwd(),
     });
@@ -300,7 +303,10 @@ describe("ClaudeAgentSession sub-agent sidechain updates", () => {
   test("tails sub-agent actions instead of dropping latest entries at cap", async () => {
     sdkMocks.query.mockImplementation(() => buildQueryMock(buildTailScenarioEvents(205)));
 
-    const session = await new ClaudeAgentClient({ logger }).createSession({
+    const session = await new ClaudeAgentClient({
+      logger,
+      resolveBinary: async () => "/test/claude/bin",
+    }).createSession({
       provider: "claude",
       cwd: process.cwd(),
     });
diff --git a/packages/server/src/server/agent/providers/claude-agent.test.ts b/packages/server/src/server/agent/providers/claude-agent.test.ts
index aba3740cc..98878b0a9 100644
--- a/packages/server/src/server/agent/providers/claude-agent.test.ts
+++ b/packages/server/src/server/agent/providers/claude-agent.test.ts
@@ -346,7 +346,7 @@ describe("ClaudeAgentClient.listModels", () => {
   const logger = createTestLogger();
 
   test("returns hardcoded claude models", async () => {
-    const client = new ClaudeAgentClient({ logger });
+    const client = new ClaudeAgentClient({ logger, resolveBinary: async () => "/test/claude/bin" });
     const models = await client.listModels({ cwd: "/tmp/claude-models", force: false });
 
     expect(models.map((m) => m.id)).toEqual([
@@ -430,7 +430,10 @@ describe("normalizeClaudeAskUserQuestionUpdatedInput", () => {
   });
 
   test("respondToPermission preserves full question input when UI returns answers-only payload", async () => {
-    const client = new ClaudeAgentClient({ logger: createTestLogger() });
+    const client = new ClaudeAgentClient({
+      logger: createTestLogger(),
+      resolveBinary: async () => "/test/claude/bin",
+    });
     const session = await client.createSession({
       provider: "claude",
       cwd: process.cwd(),
@@ -505,7 +508,7 @@ describe("ClaudeAgentSession context window usage", () => {
   const logger = createTestLogger();
 
   async function createSessionForTest(): Promise<TestClaudeSession> {
-    const client = new ClaudeAgentClient({ logger });
+    const client = new ClaudeAgentClient({ logger, resolveBinary: async () => "/test/claude/bin" });
     const session = await client.createSession({
       provider: "claude",
       cwd: process.cwd(),
@@ -605,6 +608,7 @@ describe("ClaudeAgentSession context window usage", () => {
     const nonPersistedClient = new ClaudeAgentClient({
       logger,
       queryFactory: nonPersistedQueryFactory,
+      resolveBinary: async () => "/test/claude/bin",
     });
     const nonPersistedSession = await nonPersistedClient.createSession(
       {
@@ -623,6 +627,7 @@ describe("ClaudeAgentSession context window usage", () => {
     const persistedClient = new ClaudeAgentClient({
       logger,
       queryFactory: persistedQueryFactory,
+      resolveBinary: async () => "/test/claude/bin",
     });
     const persistedSession = await persistedClient.createSession(
       {
@@ -980,7 +985,11 @@ describe("ClaudeAgentSession context window usage", () => {
         },
       ],
     ]);
-    const client = new ClaudeAgentClient({ logger, queryFactory });
+    const client = new ClaudeAgentClient({
+      logger,
+      queryFactory,
+      resolveBinary: async () => "/test/claude/bin",
+    });
     const session = await client.createSession({
       provider: "claude",
       cwd: process.cwd(),
diff --git a/packages/server/src/server/agent/providers/claude-agent.ts b/packages/server/src/server/agent/providers/claude-agent.ts
index 8145ea035..55be78869 100644
--- a/packages/server/src/server/agent/providers/claude-agent.ts
+++ b/packages/server/src/server/agent/providers/claude-agent.ts
@@ -254,6 +254,7 @@ interface ClaudeAgentClientOptions {
   logger: Logger;
   runtimeSettings?: ProviderRuntimeSettings;
   queryFactory?: typeof query;
+  resolveBinary?: () => Promise<string>;
 }
 
 interface ClaudeAgentSessionOptions {
@@ -264,6 +265,7 @@ interface ClaudeAgentSessionOptions {
   persistSession?: boolean;
   logger: Logger;
   queryFactory?: typeof query;
+  resolveBinary: () => Promise<string>;
 }
 
 type ClaudeThinkingEffort = "low" | "medium" | "high" | "xhigh" | "max";
@@ -1251,12 +1253,14 @@ export class ClaudeAgentClient implements AgentClient {
   private readonly logger: Logger;
   private readonly runtimeSettings?: ProviderRuntimeSettings;
   private readonly queryFactory: typeof query;
+  private readonly resolveBinary: () => Promise<string>;
 
   constructor(options: ClaudeAgentClientOptions) {
     this.defaults = options.defaults;
     this.logger = options.logger.child({ module: "agent", provider: "claude" });
     this.runtimeSettings = options.runtimeSettings;
     this.queryFactory = options.queryFactory ?? query;
+    this.resolveBinary = options.resolveBinary ?? resolveClaudeBinary;
   }
 
   async createSession(
@@ -1272,6 +1276,7 @@ export class ClaudeAgentClient implements AgentClient {
       persistSession: options?.persistSession,
       logger: this.logger,
       queryFactory: this.queryFactory,
+      resolveBinary: this.resolveBinary,
     });
   }
 
@@ -1298,6 +1303,7 @@ export class ClaudeAgentClient implements AgentClient {
       launchEnv: launchContext?.env,
       logger: this.logger,
       queryFactory: this.queryFactory,
+      resolveBinary: this.resolveBinary,
     });
   }
 
@@ -1381,6 +1387,16 @@ export class ClaudeAgentClient implements AgentClient {
   }
 }
 
+async function resolveClaudeBinary(): Promise<string> {
+  const found = await findExecutable("claude");
+  if (found) {
+    return found;
+  }
+  throw new Error(
+    "Claude binary not found. Install Claude Code (https://github.com/anthropics/claude-code) and ensure it is available in your shell PATH.",
+  );
+}
+
 async function resolveClaudeVersion(
   runtimeSettings?: ProviderRuntimeSettings,
 ): Promise<string | null> {
@@ -1549,6 +1565,7 @@ class ClaudeAgentSession implements AgentSession {
   private readonly persistSession?: boolean;
   private readonly logger: Logger;
   private readonly queryFactory: typeof query;
+  private readonly resolveBinary: () => Promise<string>;
   private query: Query | null = null;
   private input: AsyncMessageInput<SDKUserMessage> | null = null;
   private claudeSessionId: string | null;
@@ -1597,6 +1614,7 @@ class ClaudeAgentSession implements AgentSession {
     this.persistSession = options.persistSession;
     this.logger = options.logger;
     this.queryFactory = options.queryFactory ?? query;
+    this.resolveBinary = options.resolveBinary;
     const handle = options.handle;
 
     if (handle) {
@@ -2283,7 +2301,7 @@ class ClaudeAgentSession implements AgentSession {
       ],
     });
 
-    const claudeBinary = await findExecutable("claude");
+    const claudeBinary = await this.resolveBinary();
     this.logger.debug(
       {
         claudeBinary,
@@ -2304,7 +2322,7 @@ class ClaudeAgentSession implements AgentSession {
       allowDangerouslySkipPermissions: true,
       agents: this.defaults?.agents,
       canUseTool: this.handlePermissionRequest,
-      ...(claudeBinary ? { pathToClaudeCodeExecutable: claudeBinary } : {}),
+      pathToClaudeCodeExecutable: claudeBinary,
       // Use Claude Code preset system prompt and load CLAUDE.md files
       // Append provider-agnostic system prompt and orchestrator instructions for agents.
       systemPrompt: {
diff --git a/packages/server/src/server/agent/providers/claude-agent.voice-history-regression.test.ts b/packages/server/src/server/agent/providers/claude-agent.voice-history-regression.test.ts
index e10f1af97..af0393141 100644
--- a/packages/server/src/server/agent/providers/claude-agent.voice-history-regression.test.ts
+++ b/packages/server/src/server/agent/providers/claude-agent.voice-history-regression.test.ts
@@ -157,7 +157,7 @@ describe("ClaudeAgentSession history replay regression", () => {
 
   test("does not replay persisted history during the first live stream turn", async () => {
     const logger = createTestLogger();
-    const client = new ClaudeAgentClient({ logger });
+    const client = new ClaudeAgentClient({ logger, resolveBinary: async () => "/test/claude/bin" });
     const handle: AgentPersistenceHandle = {
       provider: "claude",
       sessionId: "history-session",
@@ -194,7 +194,7 @@ describe("ClaudeAgentSession history replay regression", () => {
 
   test("still exposes persisted history through streamHistory", async () => {
     const logger = createTestLogger();
-    const client = new ClaudeAgentClient({ logger });
+    const client = new ClaudeAgentClient({ logger, resolveBinary: async () => "/test/claude/bin" });
     const handle: AgentPersistenceHandle = {
       provider: "claude",
       sessionId: "history-session",
@@ -223,7 +223,7 @@ describe("ClaudeAgentSession history replay regression", () => {
 
   test("listCommands includes rewind command", async () => {
     const logger = createTestLogger();
-    const client = new ClaudeAgentClient({ logger });
+    const client = new ClaudeAgentClient({ logger, resolveBinary: async () => "/test/claude/bin" });
     const handle: AgentPersistenceHandle = {
       provider: "claude",
       sessionId: "history-session",
@@ -245,7 +245,7 @@ describe("ClaudeAgentSession history replay regression", () => {
 
   test("slash /rewind uses latest user message id from persisted history", async () => {
     const logger = createTestLogger();
-    const client = new ClaudeAgentClient({ logger });
+    const client = new ClaudeAgentClient({ logger, resolveBinary: async () => "/test/claude/bin" });
     const handle: AgentPersistenceHandle = {
       provider: "claude",
       sessionId: "history-session",