diff --git a/CHANGELOG.md b/CHANGELOG.md
index d3cb057..ba56747 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,8 @@
 
 ## 0.8.1 - Unreleased
 
+- Prevented oversized provider, validation, and PR-publishing timeout overrides from overflowing into one-millisecond deadlines.
+
 - Preserved observed source edits in failed patch attempts when a provider writes files before exiting with an error.
 
 - Fixed nested-project repairs to ignore their own state and sibling changes, fingerprint project-relative source paths, and record both sides of renames.
diff --git a/docs/configuration.md b/docs/configuration.md
index 9314f99..3b1e9f3 100644
--- a/docs/configuration.md
+++ b/docs/configuration.md
@@ -84,8 +84,10 @@ Environment overrides:
 - `CLAWPATCH_GH_PR_CREATE_TIMEOUT_MS` (default `300000`, or 5 minutes)
 - `CLAWPATCH_TASKKILL_TIMEOUT_MS` (Windows cleanup deadline; default `5000`, or 5 seconds)
 
-The `open-pr` timeout overrides must be positive millisecond values. Invalid values fall back to
-their defaults.
+Provider, validation, and `open-pr` timeout overrides accept `1` through
+`2147483647` milliseconds. Invalid or out-of-range values fall back to their
+defaults; fractional values are truncated. This prevents Node from turning an
+overflowing deadline into a one-millisecond timer.
 
 `CLAWPATCH_TASKKILL_TIMEOUT_MS` must be between `1` and `2147483647` milliseconds;
 invalid values fall back to 5 seconds. Fractional values are truncated. Each Windows
diff --git a/docs/providers.md b/docs/providers.md
index 5fcdbf6..f64d1bc 100644
--- a/docs/providers.md
+++ b/docs/providers.md
@@ -26,6 +26,10 @@ Provider names today:
 - `mock`: deterministic provider for tests and fixtures
 - `mock-fail`: failure provider for tests
 
+Timeout overrides must be between `1` and `2147483647` milliseconds. Invalid
+values use the default and fractional values are truncated. A provider-specific
+timeout takes precedence over `CLAWPATCH_PROVIDER_TIMEOUT_MS`.
+
 ## Codex
 
 Codex invocation:
diff --git a/src/exec.ts b/src/exec.ts
index 8ed2fb6..ea072c6 100644
--- a/src/exec.ts
+++ b/src/exec.ts
@@ -1,3 +1,4 @@
+import { parseTimeoutMs } from "./timeout.js";
 import { spawn } from "node:child_process";
 import { existsSync } from "node:fs";
 import { delimiter, extname, join } from "node:path";
@@ -19,12 +20,7 @@ const abortHandlers = new Map<NodeJS.Signals, () => void>();
 const defaultTaskkillTimeoutMs = 5_000;
 
 export function taskkillTimeoutMs(): number {
-  const configured = Number(
-    process.env["CLAWPATCH_TASKKILL_TIMEOUT_MS"] ?? String(defaultTaskkillTimeoutMs),
-  );
-  return Number.isFinite(configured) && configured >= 1 && configured <= 2_147_483_647
-    ? Math.trunc(configured)
-    : defaultTaskkillTimeoutMs;
+  return parseTimeoutMs(process.env["CLAWPATCH_TASKKILL_TIMEOUT_MS"], defaultTaskkillTimeoutMs);
 }
 
 export async function runCommand(
diff --git a/src/fix.ts b/src/fix.ts
index 340ff9a..2086564 100644
--- a/src/fix.ts
+++ b/src/fix.ts
@@ -1,3 +1,4 @@
+import { parseTimeoutMs } from "./timeout.js";
 import { loadProjectState, type AppContext } from "./app-context.js";
 import {
   changedPathsBetweenSnapshots,
@@ -116,7 +117,7 @@ export async function fixCommand(
   for (const command of validationCommands) {
     commandsRun.push(
       await runCommand(command, loaded.root, undefined, {
-        timeoutMs: validationTimeoutMs(),
+        timeoutMs: parseTimeoutMs(process.env["CLAWPATCH_VALIDATION_TIMEOUT_MS"], 600_000),
         maxOutputChars: 100_000,
       }),
     );
@@ -171,8 +172,3 @@ export async function fixCommand(
       : `clawpatch revalidate --finding ${finding.findingId}`,
   };
 }
-
-function validationTimeoutMs(): number {
-  const configured = Number(process.env["CLAWPATCH_VALIDATION_TIMEOUT_MS"] ?? "600000");
-  return Number.isFinite(configured) && configured > 0 ? configured : 600_000;
-}
diff --git a/src/mappers/go.ts b/src/mappers/go.ts
index 28c0f8e..e9806e2 100644
--- a/src/mappers/go.ts
+++ b/src/mappers/go.ts
@@ -1,3 +1,4 @@
+import { parseTimeoutMs } from "../timeout.js";
 import { readdir, readFile, realpath } from "node:fs/promises";
 import { isAbsolute, join, relative } from "node:path";
 import { runCommandArgs } from "../exec.js";
@@ -8,12 +9,7 @@ import { FeatureSeed, MapperContext, SeedFileRef, SeedTestRef } from "./types.js
 const defaultGoListTimeoutMs = 120_000;
 
 export function goListTimeoutMs(): number {
-  const configured = Number(
-    process.env["CLAWPATCH_GO_LIST_TIMEOUT_MS"] ?? String(defaultGoListTimeoutMs),
-  );
-  return Number.isFinite(configured) && configured >= 1 && configured <= 2_147_483_647
-    ? Math.trunc(configured)
-    : defaultGoListTimeoutMs;
+  return parseTimeoutMs(process.env["CLAWPATCH_GO_LIST_TIMEOUT_MS"], defaultGoListTimeoutMs);
 }
 
 export async function goSeeds(root: string, context: MapperContext): Promise<FeatureSeed[]> {
diff --git a/src/open-pr.test.ts b/src/open-pr.test.ts
index 3501f49..9db9ab9 100644
--- a/src/open-pr.test.ts
+++ b/src/open-pr.test.ts
@@ -48,6 +48,13 @@ describe("open-pr command timeouts", () => {
     expect(ghPrCreateTimeoutMs()).toBe(300_000);
   });
 
+  it("rejects overflowing publishing deadlines before passing them to Node", () => {
+    process.env["CLAWPATCH_GIT_PUSH_TIMEOUT_MS"] = "2147483648";
+    process.env["CLAWPATCH_GH_PR_CREATE_TIMEOUT_MS"] = "1e100";
+    expect(gitPushTimeoutMs()).toBe(600_000);
+    expect(ghPrCreateTimeoutMs()).toBe(300_000);
+  });
+
   it(
     "times out a hung git push instead of blocking open-pr",
     { timeout: HANG_TEST_TIMEOUT_MS },
diff --git a/src/open-pr.ts b/src/open-pr.ts
index 4474625..bd83260 100644
--- a/src/open-pr.ts
+++ b/src/open-pr.ts
@@ -1,3 +1,4 @@
+import { parseTimeoutMs } from "./timeout.js";
 import { lstat, realpath } from "node:fs/promises";
 import { relative, resolve } from "node:path";
 import { loadProjectState, type AppContext } from "./app-context.js";
@@ -505,13 +506,11 @@ function githubCli(): string {
 }
 
 export function gitPushTimeoutMs(): number {
-  const configured = Number(process.env["CLAWPATCH_GIT_PUSH_TIMEOUT_MS"] ?? "600000");
-  return Number.isFinite(configured) && configured > 0 ? configured : 600_000;
+  return parseTimeoutMs(process.env["CLAWPATCH_GIT_PUSH_TIMEOUT_MS"], 600_000);
 }
 
 export function ghPrCreateTimeoutMs(): number {
-  const configured = Number(process.env["CLAWPATCH_GH_PR_CREATE_TIMEOUT_MS"] ?? "300000");
-  return Number.isFinite(configured) && configured > 0 ? configured : 300_000;
+  return parseTimeoutMs(process.env["CLAWPATCH_GH_PR_CREATE_TIMEOUT_MS"], 300_000);
 }
 
 async function localBranchExists(gitRoot: string, branch: string): Promise<boolean> {
diff --git a/src/provider-runtime.test.ts b/src/provider-runtime.test.ts
index d938177..ccea237 100644
--- a/src/provider-runtime.test.ts
+++ b/src/provider-runtime.test.ts
@@ -24,4 +24,18 @@ describe("provider runtime policy", () => {
     expect(providerTimeoutMs("CLAWPATCH_TEST_TIMEOUT_MS", 300)).toBe(300);
     expect(providerCheckTimeoutMs()).toBe(10_000);
   });
+
+  it.each(["2147483648", "1e100", "0.5"])("rejects unsafe timer delay %s", (value) => {
+    process.env["CLAWPATCH_TEST_TIMEOUT_MS"] = value;
+    process.env["CLAWPATCH_PROVIDER_CHECK_TIMEOUT_MS"] = value;
+    expect(providerTimeoutMs("CLAWPATCH_TEST_TIMEOUT_MS", 300)).toBe(300);
+    expect(providerCheckTimeoutMs()).toBe(10_000);
+  });
+
+  it("normalizes valid fractional delays without overflowing the timer range", () => {
+    process.env["CLAWPATCH_TEST_TIMEOUT_MS"] = "1234.9";
+    expect(providerTimeoutMs("CLAWPATCH_TEST_TIMEOUT_MS", 300)).toBe(1234);
+    process.env["CLAWPATCH_TEST_TIMEOUT_MS"] = "2147483647";
+    expect(providerTimeoutMs("CLAWPATCH_TEST_TIMEOUT_MS", 300)).toBe(2147483647);
+  });
 });
diff --git a/src/provider-runtime.ts b/src/provider-runtime.ts
index 9414333..2c34044 100644
--- a/src/provider-runtime.ts
+++ b/src/provider-runtime.ts
@@ -1,10 +1,8 @@
+import { parseTimeoutMs } from "./timeout.js";
+
 export function providerTimeoutMs(envName: string, defaultMs: number): number {
   const raw = process.env[envName] ?? process.env["CLAWPATCH_PROVIDER_TIMEOUT_MS"];
-  if (raw === undefined) {
-    return defaultMs;
-  }
-  const parsed = Number(raw);
-  return Number.isFinite(parsed) && parsed > 0 ? parsed : defaultMs;
+  return parseTimeoutMs(raw, defaultMs);
 }
 
 export function providerCheckTimeoutMs(): number {
diff --git a/src/timeout.ts b/src/timeout.ts
new file mode 100644
index 0000000..41b1365
--- /dev/null
+++ b/src/timeout.ts
@@ -0,0 +1,6 @@
+export function parseTimeoutMs(value: string | undefined, fallback: number): number {
+  const milliseconds = Number(value);
+  return Number.isFinite(milliseconds) && milliseconds >= 1 && milliseconds <= 2_147_483_647
+    ? Math.trunc(milliseconds)
+    : fallback;
+}