diff --git a/src/hooks/claude-code-hooks/pre-tool-use.test.ts b/src/hooks/claude-code-hooks/pre-tool-use.test.ts
new file mode 100644
index 000000000..13770a47f
--- /dev/null
+++ b/src/hooks/claude-code-hooks/pre-tool-use.test.ts
@@ -0,0 +1,252 @@
+/// <reference types="bun-types" />
+
+import { describe, it, expect, mock, beforeEach, afterEach, spyOn } from "bun:test"
+import type { ClaudeHooksConfig } from "./types"
+import type { PreToolUseContext } from "./pre-tool-use"
+import * as dispatchHookModule from "./dispatch-hook"
+import * as logger from "../../shared/logger"
+import { executePreToolUseHooks } from "./pre-tool-use"
+
+function createContext(overrides?: Partial<PreToolUseContext>): PreToolUseContext {
+  return {
+    sessionId: "test-session",
+    toolName: "write",
+    toolInput: { file_path: "/tmp/test.md", content: "hello" },
+    cwd: "/tmp",
+    ...overrides,
+  }
+}
+
+function createConfig(matchers: ClaudeHooksConfig["PreToolUse"]): ClaudeHooksConfig {
+  return { PreToolUse: matchers }
+}
+
+describe("executePreToolUseHooks", () => {
+  let dispatchSpy: ReturnType<typeof spyOn>
+
+  beforeEach(() => {
+    dispatchSpy = spyOn(dispatchHookModule, "dispatchHook")
+    spyOn(logger, "log").mockImplementation(() => {})
+  })
+
+  afterEach(() => {
+    mock.restore()
+  })
+
+  it("#given null config #when called #then returns allow", async () => {
+    const result = await executePreToolUseHooks(createContext(), null)
+    expect(result.decision).toBe("allow")
+  })
+
+  it("#given no matching hooks #when called #then returns allow", async () => {
+    const config = createConfig([
+      { matcher: "Bash", hooks: [{ type: "command", command: "echo test" }] },
+    ])
+    const result = await executePreToolUseHooks(createContext({ toolName: "write" }), config)
+    expect(result.decision).toBe("allow")
+  })
+
+  it("#given hook returns exit code 2 #when called #then returns deny", async () => {
+    dispatchSpy.mockResolvedValue({ exitCode: 2, stdout: "", stderr: "blocked" })
+
+    const config = createConfig([
+      { matcher: "Write", hooks: [{ type: "command", command: "echo deny" }] },
+    ])
+    const result = await executePreToolUseHooks(createContext(), config)
+
+    expect(result.decision).toBe("deny")
+    expect(result.reason).toBe("blocked")
+  })
+
+  it("#given hook returns exit code 1 #when called #then returns ask", async () => {
+    dispatchSpy.mockResolvedValue({ exitCode: 1, stdout: "", stderr: "needs confirmation" })
+
+    const config = createConfig([
+      { matcher: "Write", hooks: [{ type: "command", command: "echo ask" }] },
+    ])
+    const result = await executePreToolUseHooks(createContext(), config)
+
+    expect(result.decision).toBe("ask")
+    expect(result.reason).toBe("needs confirmation")
+  })
+
+  describe("#given multiple hooks with merged config (global + project)", () => {
+    it("#when first hook allows and second hook denies #then returns deny", async () => {
+      let callCount = 0
+      dispatchSpy.mockImplementation(async () => {
+        callCount++
+        if (callCount === 1) {
+          // Global catch-all hook returns "allow" via JSON
+          return {
+            exitCode: 0,
+            stdout: JSON.stringify({ decision: "allow" }),
+            stderr: "",
+          }
+        }
+        // Project budget guard hook returns exit code 2 (deny)
+        return { exitCode: 2, stdout: "", stderr: "BUDGET EXCEEDED" }
+      })
+
+      const config = createConfig([
+        // Global catch-all (no specific matcher = matches everything)
+        { matcher: "*", hooks: [{ type: "command", command: "node pre-tool-use.mjs" }] },
+        // Project budget guard
+        { matcher: "Edit|Write", hooks: [{ type: "command", command: "bash budget-guard.sh" }] },
+      ])
+
+      const result = await executePreToolUseHooks(createContext(), config)
+
+      expect(callCount).toBe(2)
+      expect(result.decision).toBe("deny")
+      expect(result.reason).toBe("BUDGET EXCEEDED")
+    })
+
+    it("#when first hook allows and second hook also allows #then returns allow", async () => {
+      let callCount = 0
+      dispatchSpy.mockImplementation(async () => {
+        callCount++
+        if (callCount === 1) {
+          return {
+            exitCode: 0,
+            stdout: JSON.stringify({ decision: "allow" }),
+            stderr: "",
+          }
+        }
+        return { exitCode: 0, stdout: "", stderr: "" }
+      })
+
+      const config = createConfig([
+        { matcher: "*", hooks: [{ type: "command", command: "node pre-tool-use.mjs" }] },
+        { matcher: "Edit|Write", hooks: [{ type: "command", command: "bash budget-guard.sh" }] },
+      ])
+
+      const result = await executePreToolUseHooks(createContext(), config)
+
+      expect(callCount).toBe(2)
+      expect(result.decision).toBe("allow")
+    })
+
+    it("#when first hook denies #then second hook is NOT executed", async () => {
+      let callCount = 0
+      dispatchSpy.mockImplementation(async () => {
+        callCount++
+        return { exitCode: 2, stdout: "", stderr: "denied by first hook" }
+      })
+
+      const config = createConfig([
+        { matcher: "*", hooks: [{ type: "command", command: "node pre-tool-use.mjs" }] },
+        { matcher: "Edit|Write", hooks: [{ type: "command", command: "bash budget-guard.sh" }] },
+      ])
+
+      const result = await executePreToolUseHooks(createContext(), config)
+
+      expect(callCount).toBe(1)
+      expect(result.decision).toBe("deny")
+    })
+
+    it("#when first hook allows via JSON with modifiedInput #then input is passed to second hook", async () => {
+      const capturedStdin: string[] = []
+      let callCount = 0
+      dispatchSpy.mockImplementation(async (_hook: unknown, stdinJson: string) => {
+        capturedStdin.push(stdinJson)
+        callCount++
+        if (callCount === 1) {
+          return {
+            exitCode: 0,
+            stdout: JSON.stringify({
+              decision: "allow",
+            }),
+            stderr: "",
+          }
+        }
+        return { exitCode: 0, stdout: "", stderr: "" }
+      })
+
+      const config = createConfig([
+        { matcher: "*", hooks: [{ type: "command", command: "node pre-tool-use.mjs" }] },
+        { matcher: "Edit|Write", hooks: [{ type: "command", command: "bash budget-guard.sh" }] },
+      ])
+
+      await executePreToolUseHooks(createContext(), config)
+
+      expect(callCount).toBe(2)
+    })
+
+    it("#when hook returns allow with updatedInput #then modifiedInput is included in final result", async () => {
+      dispatchSpy.mockResolvedValue({
+        exitCode: 0,
+        stdout: JSON.stringify({
+          decision: "allow",
+          hookSpecificOutput: {
+            permissionDecision: "allow",
+            updatedInput: { file_path: "/tmp/modified.md" },
+          },
+        }),
+        stderr: "",
+      })
+
+      const config = createConfig([
+        { matcher: "Write", hooks: [{ type: "command", command: "bash modifier.sh" }] },
+      ])
+
+      const result = await executePreToolUseHooks(createContext(), config)
+
+      expect(result.decision).toBe("allow")
+      expect(result.modifiedInput).toEqual({ file_path: "/tmp/modified.md" })
+    })
+
+    it("#when hook returns allow with common fields #then fields are included in final result", async () => {
+      dispatchSpy.mockResolvedValue({
+        exitCode: 0,
+        stdout: JSON.stringify({
+          decision: "allow",
+          suppressOutput: true,
+          systemMessage: "Budget warning: approaching limit",
+        }),
+        stderr: "",
+      })
+
+      const config = createConfig([
+        { matcher: "Write", hooks: [{ type: "command", command: "bash checker.sh" }] },
+      ])
+
+      const result = await executePreToolUseHooks(createContext(), config)
+
+      expect(result.decision).toBe("allow")
+      expect(result.suppressOutput).toBe(true)
+      expect(result.systemMessage).toBe("Budget warning: approaching limit")
+    })
+
+    it("#when first hook allows with modifiedInput and second hook denies #then deny includes accumulated modifiedInput", async () => {
+      let callCount = 0
+      dispatchSpy.mockImplementation(async () => {
+        callCount++
+        if (callCount === 1) {
+          return {
+            exitCode: 0,
+            stdout: JSON.stringify({
+              decision: "allow",
+              hookSpecificOutput: {
+                permissionDecision: "allow",
+                updatedInput: { file_path: "/tmp/modified.md" },
+              },
+            }),
+            stderr: "",
+          }
+        }
+        return { exitCode: 2, stdout: "", stderr: "BUDGET EXCEEDED" }
+      })
+
+      const config = createConfig([
+        { matcher: "*", hooks: [{ type: "command", command: "node modifier.mjs" }] },
+        { matcher: "Edit|Write", hooks: [{ type: "command", command: "bash budget-guard.sh" }] },
+      ])
+
+      const result = await executePreToolUseHooks(createContext(), config)
+
+      expect(callCount).toBe(2)
+      expect(result.decision).toBe("deny")
+      expect(result.modifiedInput).toEqual({ file_path: "/tmp/modified.md" })
+    })
+  })
+})
diff --git a/src/hooks/claude-code-hooks/pre-tool-use.ts b/src/hooks/claude-code-hooks/pre-tool-use.ts
index 97bfaf04a..a6d03182a 100644
--- a/src/hooks/claude-code-hooks/pre-tool-use.ts
+++ b/src/hooks/claude-code-hooks/pre-tool-use.ts
@@ -73,6 +73,13 @@ export async function executePreToolUseHooks(
   const startTime = Date.now()
   let firstHookName: string | undefined
   const inputLines = buildInputLines(ctx.toolInput)
+  let accumulatedModifiedInput: Record<string, unknown> | undefined
+  let accumulatedCommonFields: {
+    continue?: boolean
+    stopReason?: string
+    suppressOutput?: boolean
+    systemMessage?: string
+  } = {}
 
    for (const matcher of matchers) {
      if (!matcher.hooks || matcher.hooks.length === 0) continue
@@ -93,10 +100,12 @@ export async function executePreToolUseHooks(
         return {
           decision: "deny",
           reason: result.stderr || result.stdout || "Hook blocked the operation",
+          modifiedInput: accumulatedModifiedInput,
           elapsedMs: Date.now() - startTime,
           hookName: firstHookName,
           toolName: transformedToolName,
           inputLines,
+          ...accumulatedCommonFields,
         }
       }
 
@@ -104,10 +113,12 @@ export async function executePreToolUseHooks(
         return {
           decision: "ask",
           reason: result.stderr || result.stdout,
+          modifiedInput: accumulatedModifiedInput,
           elapsedMs: Date.now() - startTime,
           hookName: firstHookName,
           toolName: transformedToolName,
           inputLines,
+          ...accumulatedCommonFields,
         }
       }
 
@@ -143,26 +154,40 @@ export async function executePreToolUseHooks(
             output.suppressOutput !== undefined || 
             output.systemMessage !== undefined
 
-          if (decision || hasCommonFields) {
+          if (decision === "deny" || decision === "ask") {
             return {
-              decision: decision ?? "allow",
+              decision,
               reason,
-              modifiedInput,
+              modifiedInput: modifiedInput ?? accumulatedModifiedInput,
               elapsedMs: Date.now() - startTime,
               hookName: firstHookName,
               toolName: transformedToolName,
               inputLines,
-              continue: output.continue,
-              stopReason: output.stopReason,
-              suppressOutput: output.suppressOutput,
-              systemMessage: output.systemMessage,
+              continue: output.continue ?? accumulatedCommonFields.continue,
+              stopReason: output.stopReason ?? accumulatedCommonFields.stopReason,
+              suppressOutput: output.suppressOutput ?? accumulatedCommonFields.suppressOutput,
+              systemMessage: output.systemMessage ?? accumulatedCommonFields.systemMessage,
             }
           }
+
+          // "allow" — accumulate modifiedInput and common fields, continue to next hook
+          if (modifiedInput) {
+            accumulatedModifiedInput = { ...accumulatedModifiedInput, ...modifiedInput }
+            Object.assign(stdinData.tool_input, objectToSnakeCase(modifiedInput))
+          }
+          if (output.continue !== undefined) accumulatedCommonFields.continue = output.continue
+          if (output.stopReason !== undefined) accumulatedCommonFields.stopReason = output.stopReason
+          if (output.suppressOutput !== undefined) accumulatedCommonFields.suppressOutput = output.suppressOutput
+          if (output.systemMessage !== undefined) accumulatedCommonFields.systemMessage = output.systemMessage
         } catch {
         }
       }
     }
   }
 
-  return { decision: "allow" }
+  return {
+    decision: "allow" as const,
+    ...(accumulatedModifiedInput ? { modifiedInput: accumulatedModifiedInput } : {}),
+    ...(Object.keys(accumulatedCommonFields).length > 0 ? accumulatedCommonFields : {}),
+  }
 }