web_fetch fixes

kernel/bin/agent

@@ -1765,6 +1765,40 @@ function bareWebResolveFetch(ctx) {
   return null
 }
 
+/**
+ * bundled bare-fetch rejects the fetch promise with `signal.reason` on abort.
+ * `controller.abort()` with no argument sets `reason === undefined`, so callers
+ * see `promise_rejected_with_undefined`. Always pass an explicit reason.
+ * @param {number} timeoutMs
+ */
+function bareWebTimeoutAbortReason(timeoutMs) {
+  const msg = 'web_fetch: exceeded ' + timeoutMs + 'ms (timeout)'
+  try {
+    if (typeof DOMException === 'function')
+      return new DOMException(msg, 'TimeoutError')
+  } catch {
+    /* ignore */
+  }
+  const e = new Error(msg)
+  e.name = 'TimeoutError'
+  return e
+}
+
+/**
+ * @param {AbortSignal} sig
+ */
+function bareWebSignalAbortReason(sig) {
+  try {
+    const r = /** @type {{ reason?: unknown }} */ (sig).reason
+    if (r !== undefined && r !== null) return r
+  } catch {
+    /* ignore */
+  }
+  const e = new Error('web_fetch aborted (signal)')
+  e.name = 'AbortError'
+  return e
+}
+
 /**
  * @param {AbortSignal | null | undefined} a
  * @param {AbortSignal | null | undefined} b
@@ -1774,18 +1808,23 @@ function bareWebUnionAbort(a, b) {
   if (!b) return a
   if (typeof AbortSignal.any === 'function') return AbortSignal.any([a, b])
   const c = new AbortController()
-  const fn = () => {
+  /**
+   * @param {AbortSignal} sig
+   */
+  const forward = (sig) => {
     try {
-      c.abort()
+      c.abort(bareWebSignalAbortReason(sig))
     } catch {
-      /* ignore */
+      /* ignore — second source may fire after controller already aborted */
     }
   }
   try {
-    if (a.aborted) fn()
+    const as = /** @type {AbortSignal} */ (a)
-    else a.addEventListener('abort', fn, { once: true })
+    const bs = /** @type {AbortSignal} */ (b)
-    if (b.aborted) fn()
+    if (as.aborted) forward(as)
-    else b.addEventListener('abort', fn, { once: true })
+    else as.addEventListener('abort', () => forward(as), { once: true })
+    if (bs.aborted) forward(bs)
+    else bs.addEventListener('abort', () => forward(bs), { once: true })
   } catch {
     /* ignore */
   }
@@ -2109,7 +2148,7 @@ async function bareWebRunTool(o) {
     const controller = new AbortController()
     const timer = setTimeout(() => {
       try {
-        controller.abort()
+        controller.abort(bareWebTimeoutAbortReason(timeoutMs))
       } catch {
         /* ignore */
       }
@@ -2152,7 +2191,13 @@ async function bareWebRunTool(o) {
       res = await fetchFn(currentUrl, init)
     } catch (e) {
       clearTimeout(timer)
-      const msg = bareWebFmtErr(e)
+      const msg = bareWebFmtErr(
+        e === undefined
+          ? new Error(
+              'web_fetch: fetch rejected with undefined (bare-fetch uses signal.reason; upstream abort() had no reason)'
+            )
+          : e
+      )
       return {
         ok: false,
         error: 'web_fetch: request failed: ' + msg.slice(0, 400),

kernel/etc/bare-os/posix_utilities.json

@@ -1,7 +1,7 @@
 {
   "schema": 2,
   "profileId": "bare-os-posix-like",
-  "generatedAt": "2026-04-22T05:38:34.635Z",
+  "generatedAt": "2026-04-22T05:45:50.442Z",
   "note": "Sparse POSIX Issue 7 coverage hints for /bin utilities. Omitted command names are not yet profiled here.",
   "commandIndex": [
     {

kernel/lib/bare/shell-completion.json

@@ -1,6 +1,6 @@
 {
   "schema": 1,
-  "atMs": 1776836314634,
+  "atMs": 1776836750441,
   "commands": [
     "agent",
     "arch",

packages/bare-os-coreutils/lib/agent-web-fetch.js

@@ -100,6 +100,40 @@ function bareWebResolveFetch(ctx) {
   return null
 }
 
+/**
+ * bundled bare-fetch rejects the fetch promise with `signal.reason` on abort.
+ * `controller.abort()` with no argument sets `reason === undefined`, so callers
+ * see `promise_rejected_with_undefined`. Always pass an explicit reason.
+ * @param {number} timeoutMs
+ */
+function bareWebTimeoutAbortReason(timeoutMs) {
+  const msg = 'web_fetch: exceeded ' + timeoutMs + 'ms (timeout)'
+  try {
+    if (typeof DOMException === 'function')
+      return new DOMException(msg, 'TimeoutError')
+  } catch {
+    /* ignore */
+  }
+  const e = new Error(msg)
+  e.name = 'TimeoutError'
+  return e
+}
+
+/**
+ * @param {AbortSignal} sig
+ */
+function bareWebSignalAbortReason(sig) {
+  try {
+    const r = /** @type {{ reason?: unknown }} */ (sig).reason
+    if (r !== undefined && r !== null) return r
+  } catch {
+    /* ignore */
+  }
+  const e = new Error('web_fetch aborted (signal)')
+  e.name = 'AbortError'
+  return e
+}
+
 /**
  * @param {AbortSignal | null | undefined} a
  * @param {AbortSignal | null | undefined} b
@@ -109,18 +143,23 @@ function bareWebUnionAbort(a, b) {
   if (!b) return a
   if (typeof AbortSignal.any === 'function') return AbortSignal.any([a, b])
   const c = new AbortController()
-  const fn = () => {
+  /**
+   * @param {AbortSignal} sig
+   */
+  const forward = (sig) => {
     try {
-      c.abort()
+      c.abort(bareWebSignalAbortReason(sig))
     } catch {
-      /* ignore */
+      /* ignore — second source may fire after controller already aborted */
     }
   }
   try {
-    if (a.aborted) fn()
+    const as = /** @type {AbortSignal} */ (a)
-    else a.addEventListener('abort', fn, { once: true })
+    const bs = /** @type {AbortSignal} */ (b)
-    if (b.aborted) fn()
+    if (as.aborted) forward(as)
-    else b.addEventListener('abort', fn, { once: true })
+    else as.addEventListener('abort', () => forward(as), { once: true })
+    if (bs.aborted) forward(bs)
+    else bs.addEventListener('abort', () => forward(bs), { once: true })
   } catch {
     /* ignore */
   }
@@ -444,7 +483,7 @@ async function bareWebRunTool(o) {
     const controller = new AbortController()
     const timer = setTimeout(() => {
       try {
-        controller.abort()
+        controller.abort(bareWebTimeoutAbortReason(timeoutMs))
       } catch {
         /* ignore */
       }
@@ -487,7 +526,13 @@ async function bareWebRunTool(o) {
       res = await fetchFn(currentUrl, init)
     } catch (e) {
       clearTimeout(timer)
-      const msg = bareWebFmtErr(e)
+      const msg = bareWebFmtErr(
+        e === undefined
+          ? new Error(
+              'web_fetch: fetch rejected with undefined (bare-fetch uses signal.reason; upstream abort() had no reason)'
+            )
+          : e
+      )
       return {
         ok: false,
         error: 'web_fetch: request failed: ' + msg.slice(0, 400),

packages/bare-os-coreutils/test/agent-web-fetch.test.mjs

@@ -156,3 +156,38 @@ test('bareWebFmtErr null/undefined and node-like errors', async (t) => {
   withCause.cause = new Error('inner')
   t.ok(fmt(withCause).includes('inner'))
 })
+
+test('bareWebRunTool timeout passes abort reason (matches bare-fetch contract)', async (t) => {
+  /** Simulates bare-fetch: rejects with `signal.reason` when aborted. */
+  const fetchFn = async (_url, init) => {
+    const sig = init && /** @type {{ signal?: AbortSignal }} */ (init).signal
+    if (!sig)
+      return new Promise(() => {
+        /* hang */
+      })
+    return new Promise((_res, rej) => {
+      if (sig.aborted) {
+        rej(/** @type {AbortSignal} */ (sig).reason)
+        return
+      }
+      sig.addEventListener(
+        'abort',
+        () => rej(/** @type {AbortSignal} */ (sig).reason),
+        { once: true }
+      )
+    })
+  }
+  const s = loadSandbox({ fetch: fetchFn })
+  const run = /** @type {typeof bareWebRunTool} */ (s.bareWebRunTool)
+  const out = await run({
+    ctx: { httpFetch: fetchFn },
+    url: 'https://slow.example/hang',
+    format: 'meta',
+    timeout_ms: 25
+  })
+  t.absent(out.ok)
+  const err = String(/** @type {{ error?: string }} */ (out).error || '')
+  t.ok(err.includes('web_fetch: request failed'))
+  t.ok(err.includes('timeout') || err.includes('TimeoutError') || err.includes('exceeded'))
+  t.absent(err.includes('promise_rejected_with_undefined'))
+})

packages/bare-os-seeder/kernel/bin/agent

@@ -1765,6 +1765,40 @@ function bareWebResolveFetch(ctx) {
   return null
 }
 
+/**
+ * bundled bare-fetch rejects the fetch promise with `signal.reason` on abort.
+ * `controller.abort()` with no argument sets `reason === undefined`, so callers
+ * see `promise_rejected_with_undefined`. Always pass an explicit reason.
+ * @param {number} timeoutMs
+ */
+function bareWebTimeoutAbortReason(timeoutMs) {
+  const msg = 'web_fetch: exceeded ' + timeoutMs + 'ms (timeout)'
+  try {
+    if (typeof DOMException === 'function')
+      return new DOMException(msg, 'TimeoutError')
+  } catch {
+    /* ignore */
+  }
+  const e = new Error(msg)
+  e.name = 'TimeoutError'
+  return e
+}
+
+/**
+ * @param {AbortSignal} sig
+ */
+function bareWebSignalAbortReason(sig) {
+  try {
+    const r = /** @type {{ reason?: unknown }} */ (sig).reason
+    if (r !== undefined && r !== null) return r
+  } catch {
+    /* ignore */
+  }
+  const e = new Error('web_fetch aborted (signal)')
+  e.name = 'AbortError'
+  return e
+}
+
 /**
  * @param {AbortSignal | null | undefined} a
  * @param {AbortSignal | null | undefined} b
@@ -1774,18 +1808,23 @@ function bareWebUnionAbort(a, b) {
   if (!b) return a
   if (typeof AbortSignal.any === 'function') return AbortSignal.any([a, b])
   const c = new AbortController()
-  const fn = () => {
+  /**
+   * @param {AbortSignal} sig
+   */
+  const forward = (sig) => {
     try {
-      c.abort()
+      c.abort(bareWebSignalAbortReason(sig))
     } catch {
-      /* ignore */
+      /* ignore — second source may fire after controller already aborted */
     }
   }
   try {
-    if (a.aborted) fn()
+    const as = /** @type {AbortSignal} */ (a)
-    else a.addEventListener('abort', fn, { once: true })
+    const bs = /** @type {AbortSignal} */ (b)
-    if (b.aborted) fn()
+    if (as.aborted) forward(as)
-    else b.addEventListener('abort', fn, { once: true })
+    else as.addEventListener('abort', () => forward(as), { once: true })
+    if (bs.aborted) forward(bs)
+    else bs.addEventListener('abort', () => forward(bs), { once: true })
   } catch {
     /* ignore */
   }
@@ -2109,7 +2148,7 @@ async function bareWebRunTool(o) {
     const controller = new AbortController()
     const timer = setTimeout(() => {
       try {
-        controller.abort()
+        controller.abort(bareWebTimeoutAbortReason(timeoutMs))
       } catch {
         /* ignore */
       }
@@ -2152,7 +2191,13 @@ async function bareWebRunTool(o) {
       res = await fetchFn(currentUrl, init)
     } catch (e) {
       clearTimeout(timer)
-      const msg = bareWebFmtErr(e)
+      const msg = bareWebFmtErr(
+        e === undefined
+          ? new Error(
+              'web_fetch: fetch rejected with undefined (bare-fetch uses signal.reason; upstream abort() had no reason)'
+            )
+          : e
+      )
       return {
         ok: false,
         error: 'web_fetch: request failed: ' + msg.slice(0, 400),

packages/bare-os-seeder/kernel/etc/bare-os/posix_utilities.json

@@ -1,7 +1,7 @@
 {
   "schema": 2,
   "profileId": "bare-os-posix-like",
-  "generatedAt": "2026-04-22T05:38:34.635Z",
+  "generatedAt": "2026-04-22T05:45:50.442Z",
   "note": "Sparse POSIX Issue 7 coverage hints for /bin utilities. Omitted command names are not yet profiled here.",
   "commandIndex": [
     {

packages/bare-os-seeder/kernel/lib/bare/shell-completion.json

@@ -1,6 +1,6 @@
 {
   "schema": 1,
-  "atMs": 1776836314634,
+  "atMs": 1776836750441,
   "commands": [
     "agent",
     "arch",

scripts/smoke-agent-web-fetch-bare.mjs

@@ -112,6 +112,32 @@ async function main() {
     return
   }
 
+  /** Same contract as bare-fetch: reject with `signal.reason` when aborted. */
+  async function hangUntilAbort(_url, init) {
+    const sig = init && init.signal
+    if (!sig) return new Promise(() => {})
+    return new Promise((_res, rej) => {
+      if (sig.aborted) rej(sig.reason)
+      else sig.addEventListener('abort', () => rej(sig.reason), { once: true })
+    })
+  }
+  const timeoutProbe = await bareWebRunToolFn({
+    ctx: { httpFetch: hangUntilAbort },
+    url: 'https://hang.test/',
+    format: 'meta',
+    timeout_ms: 50
+  })
+  if (timeoutProbe.ok)
+    throw new Error('[smoke-bare-web-fetch] timeout probe expected ok=false')
+  const te = String(timeoutProbe.error || '')
+  if (te.includes('promise_rejected_with_undefined'))
+    throw new Error(
+      '[smoke-bare-web-fetch] abort must carry a reason for bare-fetch: ' + te
+    )
+  if (!/timeout|TimeoutError|exceeded/i.test(te))
+    throw new Error('[smoke-bare-web-fetch] expected timeout message: ' + te)
+  console.log('[smoke-bare-web-fetch] timeout-abort contract ok')
+
   const result = await bareWebRunToolFn({
     ctx: { httpFetch: fetch },
     url: 'https://example.com/',