diff --git a/extensions/realtime-voice/src/bridge/coding-bridge.ts b/extensions/realtime-voice/src/bridge/coding-bridge.ts
index e8afe6d..0d0b309 100644
--- a/extensions/realtime-voice/src/bridge/coding-bridge.ts
+++ b/extensions/realtime-voice/src/bridge/coding-bridge.ts
@@ -129,8 +129,9 @@ export class CodingBridge {
         // throw on abort is not reliable (the subprocess can linger), and a
         // run() that never settles would leave currentTask stuck forever →
         // cancel appears to do nothing and no new task can be started.
-        const aborted = new Promise<TaskFinalSummary>((resolve) => {
-          const onAbort = () =>
+        const abortPromise = new Promise<TaskFinalSummary>((resolve) => {
+          const listener = () => {
+            ac.signal.removeEventListener("abort", listener);
             resolve({
               status: "interrupted",
               summary: "任务已取消",
@@ -139,11 +140,12 @@ export class CodingBridge {
                 unknown
               >,
             });
-          if (ac.signal.aborted) onAbort();
-          else ac.signal.addEventListener("abort", onAbort, { once: true });
+          };
+          if (ac.signal.aborted) listener();
+          else ac.signal.addEventListener("abort", listener, { once: true });
         });
         const work = this.runAgent(task, shouldResume, ac, progress, emit);
-        return Promise.race([work, aborted]);
+        return Promise.race([work, abortPromise]);
       },
     });
   }
diff --git a/packages/core/src/agent/agent-loop.ts b/packages/core/src/agent/agent-loop.ts
index 6c62d3b..c796c86 100644
--- a/packages/core/src/agent/agent-loop.ts
+++ b/packages/core/src/agent/agent-loop.ts
@@ -31,6 +31,7 @@ import {
 } from "@step-cli/utils/assistant-message.js";
 import { toErrorMessage } from "@step-cli/utils/error.js";
 import { clamp } from "@step-cli/utils/math.js";
+import { normalizeToolArguments, stableStringify } from "@step-cli/utils/json.js";
 import { truncateText } from "@step-cli/utils/text.js";
 import { estimateCompletionRequestPromptTokens } from "@step-cli/utils/token-estimator.js";
 import {
@@ -1266,38 +1267,6 @@ function createToolCallFingerprint(toolName: string, rawArgs: string): string {
   return `${toolName}:${hash}`;
 }
 
-function normalizeToolArguments(rawArgs: string): string {
-  try {
-    const parsed = JSON.parse(rawArgs) as unknown;
-    return stableStringify(parsed);
-  } catch {
-    return rawArgs.replace(/\s+/g, " ").trim();
-  }
-}
-
-function stableStringify(value: unknown): string {
-  return JSON.stringify(sortRecursively(value));
-}
-
-function sortRecursively(value: unknown): unknown {
-  if (Array.isArray(value)) {
-    return value.map((entry) => sortRecursively(entry));
-  }
-
-  if (value && typeof value === "object") {
-    const entries = Object.entries(value as Record<string, unknown>).sort(
-      ([left], [right]) => left.localeCompare(right),
-    );
-    const sorted: Record<string, unknown> = {};
-    for (const [key, child] of entries) {
-      sorted[key] = sortRecursively(child);
-    }
-    return sorted;
-  }
-
-  return value;
-}
-
 function summarizeToolData(value: unknown, maxChars: number): unknown {
   if (value === undefined) {
     return undefined;
diff --git a/packages/core/src/agent/agent-team.ts b/packages/core/src/agent/agent-team.ts
index b0e2701..52de248 100644
--- a/packages/core/src/agent/agent-team.ts
+++ b/packages/core/src/agent/agent-team.ts
@@ -1374,8 +1374,17 @@ function encodeSessionStorageKey(sessionId: string): string {
   return Buffer.from(sessionId, "utf8").toString("base64url");
 }
 
-async function sleep(delayMs: number): Promise<void> {
-  await new Promise((resolve) => setTimeout(resolve, delayMs));
+async function sleep(delayMs: number, signal?: AbortSignal): Promise<void> {
+  if (signal?.aborted) return;
+  await new Promise<void>((resolve, reject) => {
+    const timer = setTimeout(resolve, delayMs);
+    if (signal) {
+      signal.addEventListener("abort", () => {
+        clearTimeout(timer);
+        reject(new DOMException("The operation was aborted", "AbortError"));
+      }, { once: true });
+    }
+  });
 }
 
 function finalizeTeammateHarness(teammate: LiveTeammate): void {
diff --git a/packages/core/src/agent/state-machine.ts b/packages/core/src/agent/state-machine.ts
index e6f5341..e988387 100644
--- a/packages/core/src/agent/state-machine.ts
+++ b/packages/core/src/agent/state-machine.ts
@@ -35,9 +35,27 @@ export interface AgentStateSnapshot {
   priority?: AgentPriority;
 }
 
+const ALLOWED_TRANSITIONS: Record<AgentState, AgentState[]> = {
+  goal_start: ["prepare_context", "failed"],
+  prepare_context: ["model_request", "goal_complete", "failed"],
+  before_model_request_hooks: ["model_request", "failed"],
+  context_compaction: ["model_request", "failed"],
+  model_request: ["tool_execution", "final_response", "goal_complete", "failed"],
+  tool_execution: ["apply_tool_results", "model_request", "failed"],
+  apply_tool_results: ["model_request", "final_response", "goal_complete", "failed"],
+  final_response: ["goal_complete", "failed"],
+  goal_complete: [],
+  failed: [],
+};
+
 export class AgentStateMachine {
   private currentState: AgentState = "prepare_context";
   private readonly timeline: AgentStateSnapshot[] = [];
+  private readonly maxTimelineSize: number;
+
+  constructor(maxTimelineSize = 200) {
+    this.maxTimelineSize = maxTimelineSize;
+  }
 
   transition(input: {
     state: AgentState;
@@ -45,6 +63,15 @@ export class AgentStateMachine {
     toolCalls: number;
     note?: string;
   }): AgentStateSnapshot {
+    if (input.state !== this.currentState) {
+      const allowed = ALLOWED_TRANSITIONS[this.currentState];
+      if (allowed && !allowed.includes(input.state)) {
+        throw new Error(
+          `Invalid state transition: ${this.currentState} -> ${input.state}`,
+        );
+      }
+    }
+    this.currentState = input.state;
     this.currentState = input.state;
     const context = getHarnessContext();
     const snapshot: AgentStateSnapshot = {
diff --git a/packages/core/src/tools/native-impls/file-tools.ts b/packages/core/src/tools/native-impls/file-tools.ts
index 79640ac..97b53a0 100644
--- a/packages/core/src/tools/native-impls/file-tools.ts
+++ b/packages/core/src/tools/native-impls/file-tools.ts
@@ -14,6 +14,7 @@ import {
   optionalBoolean,
   optionalNumber,
   requireString,
+  safeParse,
   ToolArgError,
 } from "./parsers.js";
 
@@ -152,11 +153,6 @@ function parseEditArgs(rawArgs: string): EditArgs {
   };
 }
 
-function safeParse(rawArgs: string): unknown {
-  if (!rawArgs?.trim()) return {};
-  return JSON.parse(rawArgs);
-}
-
 async function readFileExecute(
   args: ReadArgs,
   ctx: ToolExecutionContext,
diff --git a/packages/core/src/tools/native-impls/parsers.ts b/packages/core/src/tools/native-impls/parsers.ts
index f44b87d..f760b91 100644
--- a/packages/core/src/tools/native-impls/parsers.ts
+++ b/packages/core/src/tools/native-impls/parsers.ts
@@ -72,3 +72,8 @@ export function optionalBoolean(
   }
   return value;
 }
+
+export function safeParse(rawArgs: string): unknown {
+  if (!rawArgs?.trim()) return {};
+  return JSON.parse(rawArgs);
+}
diff --git a/packages/core/src/tools/native-impls/shell-tools.ts b/packages/core/src/tools/native-impls/shell-tools.ts
index 534bea8..26f23f5 100644
--- a/packages/core/src/tools/native-impls/shell-tools.ts
+++ b/packages/core/src/tools/native-impls/shell-tools.ts
@@ -14,6 +14,7 @@ import {
   optionalNumber,
   optionalString,
   requireString,
+  safeParse,
 } from "./parsers.js";
 
 const SKIP_DIRECTORY_NAMES = new Set([
@@ -159,11 +160,6 @@ function parseGrepArgs(rawArgs: string): GrepArgs {
   };
 }
 
-function safeParse(rawArgs: string): unknown {
-  if (!rawArgs?.trim()) return {};
-  return JSON.parse(rawArgs);
-}
-
 async function bashExecute(
   args: BashArgs,
   ctx: ToolExecutionContext,
diff --git a/packages/core/src/tools/runtime.ts b/packages/core/src/tools/runtime.ts
index 117b189..bf76902 100644
--- a/packages/core/src/tools/runtime.ts
+++ b/packages/core/src/tools/runtime.ts
@@ -14,6 +14,7 @@ import type {
   ToolSpec,
 } from "@step-cli/protocol";
 import { cloneJsonSchema } from "@step-cli/utils/json-schema.js";
+import { normalizeToolArguments } from "@step-cli/utils/json.js";
 import { scoreFuzzyMatch } from "@step-cli/utils/search.js";
 import {
   buildCodeModeToolBindings,
@@ -456,11 +457,11 @@ export class ToolRuntime implements ToolRuntimeApi {
       }
 
       if (!cachedApproval && decision === "allow-always") {
-        this.approvedFingerprints.add(fingerprint);
-        if (this.approvedFingerprints.size > MAX_APPROVAL_FINGERPRINTS) {
-          this.approvedFingerprints.clear();
-          this.approvedFingerprints.add(fingerprint);
+        if (this.approvedFingerprints.size >= MAX_APPROVAL_FINGERPRINTS) {
+          const oldest = this.approvedFingerprints.values().next().value;
+          if (oldest) this.approvedFingerprints.delete(oldest);
         }
+        this.approvedFingerprints.add(fingerprint);
       }
     }
 
@@ -812,42 +813,10 @@ function createApprovalFingerprint(
     return `${toolName}:${explicitFingerprint}`;
   }
 
-  const normalizedArgs = normalizeArgsForFingerprint(rawArgs);
+  const normalizedArgs = normalizeToolArguments(rawArgs);
   return `${toolName}:${normalizedArgs}`;
 }
 
-function normalizeArgsForFingerprint(rawArgs: string): string {
-  try {
-    const parsed = JSON.parse(rawArgs) as unknown;
-    return stableStringify(parsed);
-  } catch {
-    return rawArgs.replace(/\s+/g, " ").trim();
-  }
-}
-
-function stableStringify(value: unknown): string {
-  return JSON.stringify(sortRecursively(value));
-}
-
-function sortRecursively(value: unknown): unknown {
-  if (Array.isArray(value)) {
-    return value.map((entry) => sortRecursively(entry));
-  }
-
-  if (value && typeof value === "object") {
-    const entries = Object.entries(value as Record<string, unknown>).sort(
-      ([left], [right]) => left.localeCompare(right),
-    );
-    const sorted: Record<string, unknown> = {};
-    for (const [key, child] of entries) {
-      sorted[key] = sortRecursively(child);
-    }
-    return sorted;
-  }
-
-  return value;
-}
-
 function parseApprovedFingerprints(state: unknown): string[] | null {
   if (!state || typeof state !== "object") {
     return null;
diff --git a/packages/utils/src/json.ts b/packages/utils/src/json.ts
index a272763..d4a064e 100644
--- a/packages/utils/src/json.ts
+++ b/packages/utils/src/json.ts
@@ -20,3 +20,33 @@ export function safeParseJson<T = unknown>(
     return fallback;
   }
 }
+
+function sortRecursively(value: unknown): unknown {
+  if (Array.isArray(value)) {
+    return value.map((entry) => sortRecursively(entry));
+  }
+  if (value && typeof value === "object") {
+    const entries = Object.entries(value as Record<string, unknown>).sort(
+      ([left], [right]) => left.localeCompare(right),
+    );
+    const sorted: Record<string, unknown> = {};
+    for (const [key, child] of entries) {
+      sorted[key] = sortRecursively(child);
+    }
+    return sorted;
+  }
+  return value;
+}
+
+export function stableStringify(value: unknown): string {
+  return JSON.stringify(sortRecursively(value));
+}
+
+export function normalizeToolArguments(rawArgs: string): string {
+  try {
+    const parsed = JSON.parse(rawArgs) as unknown;
+    return stableStringify(parsed);
+  } catch {
+    return rawArgs.replace(/\s+/g, " ").trim();
+  }
+}