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Macro-generate capability registrations; harden runtime timeouts and network egress; add platform + eval CI - #5

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fixes-and-improvements
Jul 13, 2026
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zac merged 25 commits into
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@zac zac commented Jul 11, 2026

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Addresses the critical issues from a repo evaluation: timeouts that couldn't interrupt running JavaScript, an unrestricted fetch (SSRF), and install docs that couldn't resolve. A high-effort self-review of the fixes then surfaced a compile blocker and several bugs, which are also fixed here.

Runtime: real timeouts & cancellation

  • Because bridge calls are synchronous, the whole promise graph settles inside one evaluateScript call, so the old wall-clock poll loop never ran while JS executed — while(true){} pinned a worker thread forever and timeoutMs was never enforced. Added ExecutionWatchdog, which installs a JavaScriptCore execution time limit so CPU-bound scripts are preemptively terminated and cancel() interrupts in-flight JS.
  • JSContextGroupSetExecutionTimeLimit/...Clear... are exported by JavaScriptCore but declared only in a private WebKit header, so they aren't visible through the public SDK module. They're reached through a new thin C shim target, CCodeModeJSC. This is JavaScriptCore's only interruption mechanism; the private-symbol dependency is documented in the README and the watchdog source so a host can make an informed App Store decision.
  • Fixed two bugs found in self-review: the settle loop could discard an already-fulfilled result and throw a spurious timeout (now checks settled state before the deadline via a shared waitForSettlement helper), and result serialization ran with the watchdog uninstalled so a runaway getter/toJSON hung the thread forever (the watchdog now stays armed with a fresh bounded budget for the decode phase).

Security: network egress policy (SSRF)

  • Added NetworkAccessPolicy on CodeModeConfiguration. The default blocks loopback, RFC 1918, link-local (including cloud metadata like 169.254.169.254), CGNAT, and unique-local destinations — including alternate/encoded IPv4 literals and IPv4-in-IPv6 (IPv4-mapped, IPv4-compatible, and NAT64) forms — plus localhost/.local/.internal names and fully-qualified trailing-dot spellings.
  • Redirect targets are re-validated before being followed; response bodies are capped (default 10 MB) via a Content-Length pre-check and streaming cancel; allowedHosts/blockedHosts and .permissive give hosts control. Allowed and denied egress destinations are written to the audit logger.

Docs

  • The README no longer instructs users to depend on from: "0.1.0" against a tagless repo (SPM can't resolve it); it documents branch-based install until 0.1.0 is tagged, and adds sections on the network access policy and the timeout/cancellation semantics.

CI

  • Added a platform-build matrix (xcodebuild for iOS and visionOS) so the UIKit presenters and the CCodeModeJSC shim compile against those SDKs — swift test on macOS never did — plus SwiftPM build caching and toolchain logging.

Tests

  • New ExecutionWatchdogTests (infinite loops, loop-in-promise-chain, uncatchable timeout, settles-at-deadline returns result, infinite getter during serialization, explicit cancel, search timeout) and NetworkAccessPolicyTests (private/loopback/link-local/CGNAT, encoded IPv4, IPv6 incl. NAT64, trailing-dot, allow/deny lists, size cap, redirect refusal).

Verification note

Authored in a Linux environment without a Swift toolchain or JavaScriptCore, so nothing here was compiled or run locally — this PR is opened specifically to let CI build and test it on macOS/iOS/visionOS. A remaining TODO.md (committed on this branch) tracks the follow-up work the evaluation surfaced (JS heap cap, concurrency bound, HealthKit-always-denied, calendar-span validation drift, Security-layer tests, and more).

🤖 Generated with Claude Code

https://claude.ai/code/session_01Az9HuLR4Sk6tP5Y924z1zF


Generated by Claude Code

claude and others added 25 commits July 11, 2026 19:59
JavaScriptCore drains the entire promise graph inside a single
evaluateScript call because bridge calls are synchronous, so the
wall-clock poll loop after evaluation could never interrupt CPU-bound
scripts: while(true){} pinned a worker thread forever and timeoutMs
was never enforced against running JavaScript.

Install a JSContextGroupSetExecutionTimeLimit watchdog per execution
whose callback re-checks the deadline and the cancellation flag every
50ms and terminates the script when either trips. Termination is
classified as EXECUTION_TIMEOUT (or SEARCH_TIMEOUT for search) and
CANCELLED, so call.cancel() now interrupts in-flight JavaScript
instead of only flipping a flag that was polled after completion.

The deadline now starts when evaluation begins rather than after the
script settles, and the dangling-promise poll loop reuses the same
deadline instead of granting a second full timeout budget.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Az9HuLR4Sk6tP5Y924z1zF
network.fetch previously accepted any HTTP(S) destination once the
capability was allowlisted, so agent-authored JavaScript could reach
loopback services, RFC 1918 hosts, and cloud metadata endpoints such
as 169.254.169.254, follow redirects from public URLs to internal
ones, and buffer arbitrarily large response bodies into memory.

Introduce NetworkAccessPolicy, injected via
CodeModeConfiguration.networkAccessPolicy:

- .standard (the default) refuses loopback, private-range, link-local,
  CGNAT, and unique-local IPv4/IPv6 destinations (including encoded
  literals like 2130706433 and 0x7f000001 via inet_aton, and
  IPv4-mapped IPv6), plus localhost and .local/.localhost/.internal
  names, and caps buffered responses at 10 MB.
- allowedHosts/blockedHosts support exact and subdomain matching, with
  explicit allowlist entries able to deliberately re-enable private
  hosts. .permissive restores the previous unrestricted behavior.
- The fetch transfer now runs through a per-task URLSession delegate
  so redirect targets are re-validated before being followed and
  oversized bodies are cancelled mid-transfer instead of buffered.
- Refusals throw structured NETWORK_POLICY_VIOLATION errors with
  repair suggestions, and both denials and successful fetch
  destinations are written to the audit logger.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Az9HuLR4Sk6tP5Y924z1zF
The install snippet told users to depend on from: "0.1.0", but the
repository has no tags, so Swift Package Manager cannot resolve that
requirement. Document the branch-based dependency as the working form
until a release is tagged, and keep the versioned form as the
preferred path once 0.1.0 exists. Also drop the deprecated name:
parameter from the .package declaration.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Az9HuLR4Sk6tP5Y924z1zF
Compile blocker: JSContextGroupSetExecutionTimeLimit and
JSContextGroupClearExecutionTimeLimit are exported by JavaScriptCore
but declared only in a private WebKit header, so the watchdog would
not compile against the public SDK module. Route both through a new
CCodeModeJSC C shim target that re-declares the exported symbols, and
document the private-API dependency in the watchdog and README.

Correctness (execution):
- The post-evaluation poll loop used 'while Date() < deadline' as its
  guard, so a script that had already fulfilled just as the deadline
  passed skipped the loop entirely and threw a spurious timeout that
  discarded a completed result. Replace both poll loops with a shared
  waitForSettlement helper that checks the settled state before the
  deadline on every iteration (and re-checks watchdog termination),
  and returns an already-settled result even a hair past the deadline.
- Result serialization ran with the watchdog uninstalled, so a result
  with a runaway getter/toJSON (e.g. { get x() { while(true){} } })
  hung the execution thread forever. Keep the watchdog installed and
  rearm it with a fresh bounded budget for the decode phase, so
  legitimate serialization still completes while runaway getters are
  terminated.
- Fold the duplicated execute/search termination + poll logic into the
  shared helper.

Security (network policy):
- Host normalization now strips a trailing root dot, so fully-qualified
  spellings like 'localhost.' or 'metadata.google.internal.' can no
  longer bypass the loopback/metadata block or the allow/deny lists.
- IPv6 private detection now also covers IPv4-compatible (::a.b.c.d) and
  NAT64 (64:ff9b::/96) embeddings of private/loopback IPv4 addresses.

Efficiency:
- Reserve the response buffer from a known Content-Length instead of
  growing it through repeated reallocations, and build the success
  audit/log summary string once.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Az9HuLR4Sk6tP5Y924z1zF
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Az9HuLR4Sk6tP5Y924z1zF
swift test on macOS never compiled the UIKit presenters or the
CCodeModeJSC watchdog shim against the iOS/visionOS SDKs, so a
platform-specific break (like the private-header symbol the shim
resolves) could land undetected. Add a platform-build matrix that runs
xcodebuild for iOS and visionOS on every PR and push, plus SwiftPM
build caching and toolchain-version logging on the deterministic job.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Az9HuLR4Sk6tP5Y924z1zF
CLRegion / CLCircularRegion are unavailable on visionOS, so the
region-scoped CLGeocoder.geocodeAddressString(_:in:) overload and the
coreLocationRegion helper failed to compile there. The package declared
.visionOS(.v2) support but was never actually built for visionOS until
the new platform-build CI job exercised it.

Use the unscoped geocodeAddressString overload on visionOS and compile
the region helper out there; other platforms keep region-scoped
geocoding. Pre-existing issue surfaced by the new CI matrix.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Az9HuLR4Sk6tP5Y924z1zF
First macOS verification run of the Linux-authored watchdog hung the whole
test suite: on macOS 26 JavaScriptCore invokes the termination callback
exactly once per installed limit, and returning false permanently disarms
the watchdog instead of re-arming it as documented. Every runaway script
(while(true), promise-chain loops, runaway getters during serialization)
therefore ran forever after the first 50ms check.

Root-caused with a minimal C reproduction against JSContextGroupSet-
ExecutionTimeLimit. The callback is now a self-referencing C function that
re-installs the time limit before returning false, restoring periodic
deadline/cancellation checks. All 8 ExecutionWatchdogTests now pass.
…an drift

Bridges parse constrained string arguments case-insensitively (lowercased()
throughout SystemUI/EventKit/Photos/FileSystem bridges), but the registry's
allowedStringValues check was exact-match, so it rejected inputs the bridges
accept. Validation now compares case-insensitively, the calendarDelete span
list includes the alias spellings EventKitBridge accepts (this_event,
future, ...), and the lowercase videoQuality duplicates that worked around
the case sensitivity are dropped.

Also adds a test pinning that no built-in registration gates on .healthKit
via requiredPermissions: the default broker can never report .granted for
HealthKit (read authorization is opaque by design), so such a registration
would fail closed unconditionally. HealthBridge does per-type authorization
itself.
Executions run on a background queue while the host may synchronously block
the main thread waiting on the result; DispatchQueue.main.sync from the
broker then deadlocks. Use main.async — the existing 10s delegate wait
already bounds the request, and if main never runs it the wait times out
and returns the current status instead of hanging.
PathPolicy: empty/whitespace paths, scoped roots, appGroup with and without
a configured root, absolute paths inside/outside allowed roots, dot-dot
escapes vs internal dot-dot, nonexistent nested paths, and symlinks that
escape vs symlinks between allowed roots. Plus round-trip/uniqueness tests
for InMemoryArtifactStore and ordering/drain/concurrency tests for
SyncAuditLogger. SystemPermissionBroker is left untested deliberately:
every path ends in a real OS framework call and needs injectable seams
first (noted in TODO).
Audit of Tools/CodeModeAuthoring (builds and passes all 14 tests on the
current toolchain) against the three built-in registration idioms and the
parallel sources of truth behind the metadata drift. Proposes a three-phase
path: converge built-ins on the typed-tool protocol with enum-typed
constrained arguments (drift-proof by construction, no macro needed), then
promote the macro into the core package as @BuiltInCodeMode generating the
decode/metadata boilerplate, then migrate per domain and delete the central
constraint and type-inference tables. Includes measured swift-syntax build
cost (24s clean, ~0 incremental, prebuilts default-on) since that was the
original reason the macro package was kept out of the core graph.
… enums

Promotes BuiltInCodeModeTool out of SimpleBuiltInCodeModeProviders.swift as
the standard registration idiom, extended with capability IDs, JS name
aliases, and required permissions. Adds CodeModeStringEnum: a constrained
string argument is declared once as an enum, and the advertised
allowedStringValues, the case-insensitive/alias-aware decode, and the bridge
parsing all derive from that declaration, so they cannot drift.

Migrates the EventKit domain (9 registrations, 5 enums) to prove the shape:
EventKitBridge and SystemUIBridge now parse span/operation/picker styles
through the shared enums, and the four EventKit-domain rows are deleted from
the central CapabilityArgumentConstraints.defaults table. Keychain, location,
and weather tools converge on the same protocol; the raw-CodeModeRegistration
and builtInCapability: glue idioms are gone.

Adds constrainedArgumentMetadataIsCoherentForAllRegistrations (every
constrained argument must be a declared argument) and reworks the span test
to pin enum <-> descriptor <-> bridge agreement. Transitional tools carry a
raw passthrough because bridges still consume raw dictionaries; the Phase 2
macro generates decode and the argument metadata, which is where the
line-count win lands. 207 tests pass.
Folds Tools/CodeModeAuthoring into the root package: CodeModeMacros becomes
a macro target of the main package (swift-syntax 601.0.1, prebuilts
default-on; eval CLI cold build measured at 29s) and the host-facing
@CodeMode surface ships as the CodeModeAuthoring product. The same compiler
plugin now also provides the internal @BuiltInCodeMode + @ToolParam macros.

@BuiltInCodeMode generates the mechanical members of a BuiltInCodeModeTool
from its Arguments struct: identity statics, the codeModeArguments metadata
list, and decode(arguments:). Curated prose, permissions, and
call(arguments:context:) stay hand-written. Field types the macro does not
recognize as JSON primitives are emitted through CodeModeStringEnum-
constrained overloads, so the compiler enforces the semantics on the
expansion and constraint metadata derives from the enum. A trailing
un-annotated raw: [String: JSONValue] receives the canonicalized passthrough
transitional tools need while bridges consume raw dictionaries.

The EventKit domain is converted to the macro (its hand-written decode and
argument lists are deleted). Adds five expansion tests (generated source +
diagnostics), behavioral decode tests, and a metadata baseline test pinning
the advertised surface of remindersWrite. CI xcodebuild jobs get
-skipMacroValidation for the package-local plugin. 229 tests pass.
CapabilityMetadataGoldenTests pins every registration's full advertised
surface (jsNames, prose, permissions, argument lists/types/hints,
constraints, resultSummary) against a committed 115-capability JSON
baseline; CODEMODE_REGENERATE_GOLDEN=1 regenerates it, and the JSON diff
becomes the review artifact for registration refactors. This is the safety
rail that makes the remaining domain migrations mechanically verifiable.

PHASE3-HANDOFF.md is the self-contained work spec for converting the seven
remaining CapabilityRegistrations files to @BuiltInCodeMode: per-registration
recipe (including the effective-type rule for inferred/.any arguments and
the constrained-enum rewiring pattern), domain order with per-domain notes,
the allowed golden-diff categories, and hard rules (no prose rewording, no
permission-ownership changes, skip-don't-improvise). 230 tests pass.
Converts all 12 interaction-UI capabilities (share, quicklook, camera
capture/scan, mail, messages, print, web, auth, alert, prompt, settings) to
macro-authored tools in SystemUICodeModeTools.swift; the registration file is
now a thin list. Introduces 8 CodeModeStringEnums for the constrained values
(MediaTypeFilter, CameraDevice, CameraFlashMode, CameraVideoQuality,
DataScannerMode, DataScannerQualityLevel, PrintOutputType, AlertPreferredStyle)
and rewires SystemUIBridge's own lowercased() validations to parse through
them, making each enum the single source of truth. The cameraUICapture /
cameraUIScanData / printUIPresent / uiAlertPresent rows are deleted from the
central CapabilityArgumentConstraints.defaults table.

AlertPreferredStyle keeps the all-lowercase 'actionsheet' spelling as an alias
because SystemUIBridge accepts it (SystemUIBridge.swift validateAlertArguments);
CameraVideoQuality's canonical spellings survive the presenters' lowercasing
(UIKitSystemUIPresenter.videoQuality/printOutputType), so raw-passthrough
canonicalization is behavior-preserving.

Golden diff: one allowed category only — argumentHints gained title/message
entries for uiPromptPresent (which advertised no hints for them before);
values match the uiAlertPresent wording. 230 tests pass.
Converts the 10 filesystem capabilities (list, read, write, move, copy,
delete, stat, mkdir, exists, access) to macro-authored tools in
FileSystemCodeModeTools.swift; the filesystem section of +Core.swift is now a
thin list. No constrained values, so no enums and no bridge rewiring.

networkFetch is left on the flat-init idiom (PHASE3-SKIP comment): it declares
nested dotted-path arguments (options.method, options.headers, …) that the
flat @BuiltInCodeMode Arguments model cannot express without changing the
advertised optionalArguments list, and its options.responseEncoding constraint
stays in the central defaults table. Keychain already delegates to the
Phase-1 converted builtins and is untouched.

Golden diff: empty — every filesystem argument already had a hint, and types
match the inferred baseline. 230 tests pass.
…eMode

Converts all 13 capabilities (contacts read/search/pick/present/presentNew,
photos read/export/pick/limited-picker, documents pick/export/openIn/scan) to
macro-authored tools; both registration functions are now thin lists.

Constrained values: photosRead and photosUIPick reuse MediaTypeFilter (from
domain 1); contactsUIPick gets a new ContactPickerMode enum. Their three rows
are deleted from the central defaults table. Rewires the owning parsers to the
enums: PhotosBridge.read (mediaType -> MediaTypeFilter), SystemUIBridge
validateContactPickerArguments (mode -> ContactPickerMode); photosUIPick's
mediaType already validated through MediaTypeFilter via the shared
validatePhotoPickerArguments rewired in domain 1.

Also decouples constraintValidationMatchesCaseInsensitively from the removed
contactsUIPick table row by constructing the constraints inline — it tests the
generic validate() matching, which is unchanged.

Golden diff: empty — advertised allowedStringValues are identical to the
former table rows, all argument types match the inferred/declared baseline,
and every argument already had a hint. 230 tests pass.
Converts all 19 vision/notifications/alarm/health/home/media capabilities to
macro-authored tools in SystemServicesCodeModeTools.swift; the six
registration functions are now thin lists. No constrained values in this
domain, so no enums, no bridge rewiring, no table changes.

Permission declarations are preserved exactly: notifications (.notifications),
alarms (.alarmKit), home (.homeKit); vision/media declare none; and the three
health tools declare no requiredPermissions — HealthKit read authorization is
opaque so HealthBridge does its own per-type auth, and the
noBuiltInRegistrationGatesOnHealthKitPermission invariant test still passes.
homeWrite's value keeps its .any type (declared as JSONValue).

Golden diff: empty — every argument already had a hint and types match the
declared/inferred baseline. 230 tests pass.
…o @BuiltInCodeMode

Converts all 15 capabilities in +CloudPushSpeech.swift (6 CloudKit, 5 remote
notification, 4 speech) to macro-authored tools; the three sub-functions are
now thin lists (the bigTicketAppleRegistrations aggregator is unchanged).

The four database ops (queryRecords/saveRecord/deleteRecord/subscribe) share a
new CloudKitDatabase enum (private/shared/public); its row is deleted from the
central defaults table and SystemCloudKitMapping.databaseName/database now
parse through the enum, so the advertised, decoded, and system-client-mapped
values share one source. The mapping test (default private, shared, invalid
archive) still passes.

Golden diff: one allowed category — cloudKitSubscriptionSave gained
containerIdentifier and zoneID hints (it advertised none for them); values are
copied verbatim from the sibling CloudKit registrations. 230 tests pass.
…nCodeMode

Converts all 18 capabilities in +IntentsModelsActivityMaps.swift to
macro-authored tools; the four sub-functions are now thin lists.

Constrained values: activityEnd gets an ActivityDismissalPolicy enum
(default/immediate) and mapsRouteEstimate/mapsOpen share a MapsTransportType
enum (automobile/walking/transit/any); both rows are deleted from the central
defaults table. transportType parsing in SystemMapsMapping.transportTypeName
is rewired through the enum (its allowedTransportTypes constant is removed);
dismissalPolicy has no in-tree consumer (host ActivityClient handles it), so
the enum gates it at the registry.

The type-inference trap: foundationModelsGenerate.prompt is absent from the
argument-type table, so its historical advertised type is 'any' — declared as
JSONValue to preserve it, not String.

Golden diff: one allowed category only — argumentHints gained entries for
seven registrations that advertised no hints for those arguments (activityList,
activityUpdate, activityEnd, activityPushTokenRead, mapsReverseGeocode, and the
departureDate/arrivalDate and transportType gaps on the maps route/open tools).
No types, constraints, or existing prose changed. 230 tests pass.
…main)

Converts all 18 music/passKit/storeKit capabilities to macro-authored tools;
the three sub-functions are now thin lists. Only musicPlaybackControl.action
is constrained (a new MusicPlaybackAction enum: play/pause/stop/skipToNext/
skipToPrevious/playCatalog/playLibrary); its row is deleted from the central
defaults table. Host clients stay authoritative for playback semantics, so no
bridge rewiring — the enum only gates the advertised value set at the registry.

The type-inference trap: musicPlaylistWrite.name is absent from the argument-
type table, so its historical advertised type is 'any' — declared as JSONValue
to preserve it, not String.

Also makes registryValidationRejectsDescriptorConstrainedValuesBeforePermissions
self-contained: it built a synthetic musicPlaybackControl descriptor that relied
on the removed defaults(for:) row, so it now passes an explicit
argumentConstraints and still verifies constraint-before-permission ordering.

Golden diff: one allowed category only — argumentHints gained entries for five
registrations that advertised none for those arguments (musicCatalogDetails
countryCode, musicPlaybackControl startPlaying, musicPlaylistWrite description,
passKitApplePayPresent timeoutMs, passKitPassPresent identifier+timeoutMs).

This completes Phase 3: 114 of 115 capabilities are now macro-authored;
networkFetch alone stays on the flat init (dotted-path arguments). Updates
TODO.md and PLAN-registration-macros.md to reflect completion. 230 tests pass.
The scheduled (daily) run only fired 'codemode-eval plan', which is pure
arithmetic (scenarios x repeat x maxTurns) printed to a log — no live model
calls, no compare, no artifact, deterministic output. It burned a macOS runner
daily for zero signal. Removed the 'schedule' trigger entirely.

Deterministic evals + iOS/visionOS platform builds stay continuous: PRs and
pushes to main (merges), unchanged.

Replaces the no-op llm-plan job with a real llm-live regression gate, manual
only (workflow_dispatch): it previews the budget, then — when a WAVELIKE_API_KEY
secret is present and the CLI is built with the private overlay (real
codemode-eval llm vs the LLMUnavailable stub) — runs the core/failures suites
live and compares each against its committed baseline, failing on pass-rate or
exact-capability regression. Absent those it skips the live steps with a warning
rather than pretending. This encodes the intended pipeline so it goes fully live
once the private Wavelike wiring + secret land, with no further workflow edits.

Updates EVALS.md CI Policy to match.
@zac zac changed the title Harden runtime timeouts and network egress; add platform CI Macro-generate capability registrations; harden runtime timeouts and network egress; add platform + eval CI Jul 13, 2026
@zac
zac merged commit 95f9918 into main Jul 13, 2026
4 checks passed
@zac
zac deleted the fixes-and-improvements branch July 13, 2026 02:30
zac added a commit that referenced this pull request Jul 26, 2026
The shipping default was `URLSession.shared`, which reads
`HTTPCookieStorage.shared` and `URLCredentialStorage.shared`. Every script
request therefore rode whatever the host app was already logged in to —
authenticated session-riding against any origin with a live cookie — and a
`Set-Cookie` in a script-fetched response poisoned the app's cookie jar. The
tests all passed an `.ephemeral` session, so the shipping default was the one
configuration never exercised.

`network.fetch` now defaults to `NetworkBridge.isolatedSession`: ephemeral, with
no cookie storage, no credential storage, no shared cache, and cookies disabled
outright. Per-request cookie handling is disabled too, so a host that supplies
its own session still does not attach its jar.

Caller-supplied `Cookie`, `Authorization`, and `Proxy-*` headers were copied to
the wire verbatim; they are now refused with `NETWORK_POLICY_VIOLATION` and
audited. `NetworkAccessPolicy.allowsCredentialHeaders` re-enables them for hosts
whose scripts legitimately call an authenticated API, and `.permissive` sets it,
keeping that opt-out a faithful "old behavior" switch.

Review finding P0 #5.
zac added a commit that referenced this pull request Oct 21, 2026
…#7)

* Make the host, not the model, the capability boundary

`allowedCapabilities`/`allowedCapabilityKeys` are model-authored tool arguments,
and nothing in the package narrowed them, so a host that piped tool JSON straight
into `executeJavaScript` — the README Quick Start shape — granted whatever the
script declared for itself.

Adds `CodeModeConfiguration.capabilityGrant` (`CapabilityGrant`), intersected
with the request before the invocation context is built, so the effective set is
always requested ∩ granted. Defaults to `.unrestricted` for source compatibility.
Withheld identifiers produce a `CAPABILITY_WITHHELD_BY_HOST` diagnostic, and the
resulting `CAPABILITY_DENIED` tells the model the denial is not repairable by
widening its own allowlist, so it stops escalating.

Also closes the aliasing hole: `allowedCapabilityKeys` accepts arbitrary strings
and is not validated against `CapabilityID` at decode time, but `invokeBuiltIn`
honoured it and `registeredFunction(for: key)` resolved built-ins first — so
`{"allowedCapabilities": [], "allowedCapabilityKeys": ["keychain.read"]}` reached
the built-in keychain bridge past any host vetting only the typed field. Built-ins
are now gated by `allowedCapabilities` alone, the key namespace resolves custom
providers only, and a key that spells a built-in is rejected on the provider path
as defense in depth. Granting a built-in by its `CapabilityID` is unchanged.

Review findings P0 #1 and #2.

* Make adversarial number handling total instead of trapping

`Int.init(_: Double)` traps on non-finite and out-of-range input, and every
number reaching these paths is attacker-controlled: `JSONValue.intValue` backs 48
`.int(...)` call sites, and `JavaScriptExecutionRequest.decodeTimeoutMs` runs on
model-authored tool JSON before any script executes. `{"timeoutMs": 1e300}` or
`fetch(url, { timeoutMs: 1e300 })` killed the host process in-process.

- `JSONValue.intValue` goes through a total `exactInt(from:)` that rejects NaN,
  infinity, and out-of-range magnitudes; in-range values truncate toward zero as
  before.
- `decodeTimeoutMs` rejects doubles and numeric strings it cannot represent.
- `timeoutMs` is clamped to the 1...60000 bounds the tool schema already
  advertises, in both the memberwise init and the decoder, so an over-large
  budget yields the ceiling rather than an unbounded run.
- A declared-`.number` argument must now be finite: the type check rejects
  non-finite JSON numbers, and `coerceScalarString` no longer accepts
  `"inf"`/`"nan"`, which `Double.init(String)` parses happily.

Review finding P0 #3.

* Stop fs.move/fs.copy from recursively deleting their destination

Both operations unconditionally recursive-deleted any existing destination, with
no overwrite flag and no directory check, and containment alone admits a root:
`DefaultPathPolicy.resolve(path: "documents:")` yields the documents root and
`isAllowed` accepts it via `path == allowed`. So
`apple.fs.move({ from: 'tmp:junk.txt', to: 'documents:' })` removed the user's
entire Documents directory. `fs.delete` already gated directories correctly, so
the three operations disagreed.

Destinations now go through one guard shared by move and copy: a sandbox root is
refused outright, an existing destination requires `overwrite: true`, and an
existing *directory* additionally requires `recursive: true` — the same shape
`fs.delete` enforces. `fs.delete` picks up the root check too, since
`{path: 'documents:', recursive: true}` had the same reach.

Also bounds and clarifies file IO:
- `CodeModeConfiguration.fileSystemLimits` caps `fs.read`/`fs.write` (16 MB
  default). A 2 GB file in `documents:` was previously read whole and
  base64-serialized. The read cap is checked against stat before the read, so it
  does not spend the memory it exists to protect; the write cap is checked before
  the parent directory is created, so a refused write leaves nothing behind.
- A `utf8` read of undecodable bytes now fails with a repair suggestion instead
  of silently returning `""`, which told the script the file was empty.
- `encoding` is a `CodeModeStringEnum`, so the catalog advertises
  `allowedStringValues` instead of leaving the constraint in prose.

`PathPolicy` gains `allowedRoots` (defaulted empty, so custom policies still
compile) to make "is this a root" answerable.

Golden metadata baseline regenerated; the diff is the four fs entries above.

Review finding P0 #4, plus the `fs.read` encoding-constraint item from P2.

* Strip ambient authority from network.fetch

The shipping default was `URLSession.shared`, which reads
`HTTPCookieStorage.shared` and `URLCredentialStorage.shared`. Every script
request therefore rode whatever the host app was already logged in to —
authenticated session-riding against any origin with a live cookie — and a
`Set-Cookie` in a script-fetched response poisoned the app's cookie jar. The
tests all passed an `.ephemeral` session, so the shipping default was the one
configuration never exercised.

`network.fetch` now defaults to `NetworkBridge.isolatedSession`: ephemeral, with
no cookie storage, no credential storage, no shared cache, and cookies disabled
outright. Per-request cookie handling is disabled too, so a host that supplies
its own session still does not attach its jar.

Caller-supplied `Cookie`, `Authorization`, and `Proxy-*` headers were copied to
the wire verbatim; they are now refused with `NETWORK_POLICY_VIOLATION` and
audited. `NetworkAccessPolicy.allowsCredentialHeaders` re-enables them for hosts
whose scripts legitimately call an authenticated API, and `.permissive` sets it,
keeping that opt-out a faithful "old behavior" switch.

Review finding P0 #5.

* Bound what a single execution can accumulate in memory

Nothing capped output. The whole result was stringified, copied into a Swift
String, and re-decoded; every console.log was retained and then copied again into
each CodeModeToolError; the events AsyncStream used the default unbounded
buffering, so a chatty script whose events the host was not draining buffered
without limit. One script could jetsam an iOS host.

`CodeModeConfiguration.executionLimits` bounds all of it, and every limit
degrades rather than fails — for an LLM consumer a truncated result with a
diagnostic beats an out-of-memory kill:

- Result size is measured *inside* JS, so an oversized value is never brought
  across. Over the limit, the output is replaced by a still-parseable descriptor
  (`__codeModeTruncated`, character count, limit, preview) plus a
  RESULT_TRUNCATED diagnostic suggesting fs.write + return the path.
- Retained logs are capped at the first N with a one-time LOG_LIMIT_REACHED
  notice; streaming stays live past the cap since it is the retained copy that
  costs. Over-long messages are elided in the middle, keeping head and tail.
- Diagnostics and permission events are capped.
- The events stream uses `.bufferingNewest(n)`.

Two watchdog findings in the same code path:
- The serialization re-arm used `max(timeoutMs, 1000)`, so a 60s execution bought
  another 60s for JSON.stringify. It is `min` against a fixed 1s budget now,
  which is what "bounded budget" meant.
- `watchdog.termination` was never consulted after the re-arm, so a runaway
  getter surfaced as `INVALID_RESULT: must be JSON-serializable` and steered the
  model to the wrong fix. It now reports EXECUTION_TIMEOUT/CANCELLED naming the
  serialization phase.

Review finding P0 #6 and the first two P2 items.

* Fix two threading bugs in the permission and EventKit paths

**Location.** `CLLocationManager` delivers delegate callbacks on the run loop of
the thread that *created* it, and the bridge's GCD workers have none. The manager
and delegate were constructed on the execution thread with only
`requestWhenInUseAuthorization()` dispatched to main, so
`locationManagerDidChangeAuthorization` never arrived: every first-time grant
burned the full 10s wait and then reported from a status re-read that races the
TCC write, so a user who tapped Allow could still get `notDetermined`. Creation,
delegate assignment, and the request now all happen on main, the delegate holds
the manager alive (CoreLocation does not retain its delegate, and the manager
would otherwise die with the dispatched block), and the resolved status comes
from the callback rather than a re-read.

**Reminders.** `EventKitBridge.readReminders` wrote `var result` from EventKit's
completion queue, read it after a `semaphore.wait` whose timeout result was
discarded, and returned `.array([])` on timeout — a data race with the late
callback, and a result the script could not tell apart from "no reminders".

Both now go through one `CompletionWait` helper that either returns the value the
callback delivered or throws `BridgeError.timeout`, keeping the box alive so a
late callback writes somewhere harmless. The broker's `request*` methods are
migrated to the same helper, which also collapses their duplicated
availability-branch semaphore plumbing.

Review findings P0 #7 and #8.

* Work through the P2 correctness and polish findings

**One ISO 8601 parser.** Health and Alarm fell back to `.withFractionalSeconds`;
EventKit, Notifications, and the system-UI validators used a bare
`ISO8601DateFormatter`. So `2026-07-24T10:00:00.000Z` — what JavaScript's
`toISOString()` emits, and what models therefore produce by default — parsed in
some bridges and not others. Worse, `calendar.read`/`reminders.read` then did
`isoDate(...) ?? Date()`, handing the script a plausible but wrong window with no
diagnostic. `CodeModeDate` is now the only parser, and a present-but-unparseable
date is an error; only an absent one takes the default.

**HealthKit stops claiming access it cannot verify.** `requestAuthorization`'s
`success` means the sheet flow completed — HealthKit deliberately hides read
denial so an app cannot infer a condition from it — but the bridge reported
`granted: true`, and mapped `getRequestStatusForAuthorization == .unnecessary`
("nothing left to ask") to `.granted`. Reads then returned [] while the
transcript claimed permission. It now reports flow completion, per-type *share*
authorization (the only part HealthKit answers), and says plainly that read
authorization is undisclosed. The broker's fail-closed `healthKitStatus` is
untouched.

**HomeKit status no longer prompts.** Constructing `HMHomeManager` is what
triggers the TCC dialog, and `homeKitStatus()` built one inside `status(for:)`
while `requestHomeKitPermission` called it twice and built a third. Status now
answers from a shared manager if one exists and otherwise fails closed with
`.notDetermined`, routing the caller to the request path where a prompt belongs.

**Network and browser destinations.** Bare single-label hosts (`router`,
`intranet`, `wpad`, `nas`) resolve onto the LAN through the DHCP search domain
but fell through to "allowed"; they are refused like `*.local`, and an explicit
`allowedHosts` entry still wins. `web.ui.present` and `auth.ui.webAuthenticate`
now consult `NetworkAccessPolicy` — opening a page in a browser was exempt from
the policy governing fetch — and `auth.ui.webAuthenticate` defaults to an
ephemeral browser session, so a script-started OAuth flow no longer begins
already signed in as the user.

**Crash and containment fixes.** `EKEvent.calendar` (`EKCalendar!`, nil for
orphaned events) and `EKReminder.title` (`String!`) are nil-coalesced like every
neighbouring field. Two force-unwrapped `URL(string:)!` in the public
`UIKitSystemUIPresenter` throw instead. A symlink to a *nonexistent* out-of-root
target passed containment, because `fileExists` follows links (so the link read
as a missing component) and `resolvingSymlinksInPath` leaves a dangling link
unchanged; both halves are fixed, with a bounded walk for cycles.

**Concurrency honesty.** `Task.isCancelled` was checked from plain GCD workers
where it is always false — removed, leaving the controller that `cancel()`
actually sets. The watchdog deadline is a `ContinuousClock.Instant`, so an NTP
adjustment cannot move it. `JavaScriptExecutionCall` cancels on deinit, so a
dropped call stops instead of running to completion in the background, and
`result` no longer spawns a `Task.detached` per access.

**Diagnostics.** Error-severity diagnostics were recorded but never emitted, so a
host watching the stream saw every diagnostic except the ones that mattered most.

**Path arguments.** `speech.file.transcribe` and `passkit.pass.add` left the raw
script-supplied `path` in the dictionary alongside `resolvedPath`; the raw value
is now replaced, so a host adapter reading `path` cannot bypass the path policy.

Golden baseline regenerated for the two web-auth metadata strings.

* Stop multi-step eval scenarios from masking a failed step

`EvalRunner` overwrote `executionOutput`/`Logs`/`Diagnostics`/`observedError` on
every step and did not stop on an intermediate error, so validation only ever saw
the last one: a scenario could pass while step 1 failed in a way step 2 masked,
and step 1's logs — the evidence for why — were discarded before anyone could
read them.

Logs and diagnostics now accumulate across steps. The graded output and error are
still the last step's, so a successful repair step clears the failure that
preceded it, but an unexpected failure stops the run.

"Unexpected" needs to be explicit, because repair scenarios deliberately call a
helper wrong and fix it from the structured error — that first failure is the
whole point. `CodeModeEvalExecuteStep.expectsFailure` marks those, and
`filesystemRepairAfterInvalidArguments` moves to explicit steps to use it. Every
other step failing now ends the scenario.

* Record the decision to keep swift-syntax in the core target

REVIEW.md P1 #12 asks the CodeMode target to drop its CodeModeMacros
dependency by checking in the 117 expanded tool definitions. Declined, with
reasoning in TODO.md: the cited cost is already measured and mitigated
(prebuilt swift-syntax is default-on, and the version range is already widened
for the one named conflict), the migration is one-way and strips @ToolParam
hints off the property declarations, and it pulls against findings #11 and #13,
which both want more generation from this metadata.

* Generate TypeScript declarations from the capability registry

Cloudflare's central Code Mode insight is that models write markedly better code
against real types, and nothing here emitted any: the model got a flat
`argumentTypes` map of six coarse cases, a prose `resultSummary`, and constraints
that lived only in hint text it had to notice and obey.

The registry already holds names, required/optional arguments, types, enum
constraints, and hints, so `TypeScriptDeclarations` emits `.d.ts` from exactly
that. Constrained arguments become string-literal unions — the constraint *is*
the type. Dotted argument paths (`options.timeoutMs`) rebuild into nested object
types. Hints become doc comments; capability ID, result summary, aliases, and the
example ride along.

Two entry points:
- `JavaScriptAPIReference.dts` — per capability, so code-driven search stays the
  filter and TypeScript becomes the payload. The tool description now points the
  model at it.
- `CodeModeAgentTools.typeDeclarations()` — the whole platform-filtered surface,
  namespaced, for a host system prompt. `capabilities()` is exposed alongside it,
  which hosts also needed for consent UI and for building a `CapabilityGrant`.

Results are typed `CodeModeValue`: built-in bridges return untyped JSON
dictionaries, so a narrower result type would be a fiction. Per-capability result
schemas can tighten this later without changing the shape.

Generating declarations surfaced real catalog-vs-binding drift, which is fixed
rather than described (partial #11 — the hand-written bootstrap stays for now):
- `apple.keychain.{get,set,delete}` advertised object arguments while the wrapper
  took positional strings, and the catalog's own example showed the positional
  form. Code written from the metadata sent "[object Object]" as the key. The
  wrappers accept both spellings; examples move to the object form.
- `fs.promises.rename`/`copyFile` could not pass the `overwrite`/`recursive` flags
  that `fs.move`/`fs.copy` now require, so those aliases failed on any existing
  destination.
- `apple.location.getCurrentPosition`/`getPermissionStatus` discarded a caller's
  arguments outright; they now default the mode instead of forcing it.
- The tool description claimed "apple.* helpers take one object argument" as a
  blanket rule; it now scopes positional to `fs.promises.*` and points at `dts`.

The Node-compatibility globals stay in a hand-authored preamble, because their
positional convention is not something the catalog can express — that gap is
exactly what #11 exists to close.

* Give the runtime a real timer loop and stop hiding swallowed failures

Partial P1 #9. The full async bridge ABI — Swift-resolved promises, concurrent
native calls, bounded execution slots — remains a milestone; these are the parts
that are wrong *within* the synchronous model, including both cheap wins the
review called out as available immediately.

**setTimeout was a lie.** It invoked the callback synchronously and ignored the
delay, so three things were wrong at once: `clearTimeout` could never cancel, an
error thrown by a callback propagated to setTimeout's *caller* rather than being
an uncaught task error, and `await new Promise(r => setTimeout(r, 2000))` — the
standard backoff — became a hot loop hammering remote APIs through `fetch`.

There is now a real timer queue drained by the host between JavaScript turns:
callbacks are deferred, delays are honoured, registration order breaks ties,
`clearTimeout` works, and a throwing callback becomes a `TIMER_CALLBACK_ERROR`
diagnostic. Waiting stays responsive to `cancel()` and bounded by `timeoutMs`, so
a 30s timer under a 100ms budget still times out at 100ms.

**Unsettleable promises are diagnosed, not waited out.** `waitForSettlement`
polled a state that, under this model, only a timer can change — microtasks have
already drained inside `evaluateScript` and no native call is outstanding. With no
timer queued the promise is *provably* unsettleable, so it reports
`JS_RUNTIME_ERROR: ... can never settle` immediately instead of sleeping a thread
to the deadline for a result that cannot arrive.

**Swallowed bridge failures are visible.** Nothing installs an unhandled-rejection
hook, so a forgotten `await` — the most common LLM JavaScript mistake — discarded
a `CAPABILITY_DENIED` and the agent was told the run succeeded. A script that
completes successfully despite failed bridge calls now carries a
`BRIDGE_FAILURES_NOT_SURFACED` warning naming them. It is a warning, not an error,
because a deliberate try/catch is indistinguishable from a missing await.

Tool description and README updated: setTimeout is no longer described as
synchronous, `Promise.all` is documented as sequential (which it is, until the
async ABI lands), and the new diagnostics have repair guidance. The eval suite
splits the old "unresolved promises time out" scenario into an unsettleable-promise
case and a genuine CPU-bound timeout, and gains a timer-backoff scenario.

* Bound concurrent executions and cover the concurrent path with tests

The execution queue is `.concurrent` with no width limit, and each execution
blocks its thread for the whole run, so thirty parallel `executeJavaScript` calls
meant thirty blocked GCD threads and thirty live JavaScriptCore VMs. There was
also no concurrent-execution test at all, despite the concurrent queue being a
core design point.

`ExecutionLimits.maxConcurrentExecutions` (default 8) gates the queue with a
semaphore acquired on the worker rather than before dispatch, so the caller's
async context is never blocked and waiting for a slot does not eat the
per-execution `timeoutMs`.

Two tests: twelve executions through three slots all complete with correct,
isolated results and no state carried between contexts; and executions beyond the
limit queue rather than fail.

Closes the remaining "bound on concurrent executions" item in TODO.md §1.

* Unfreeze the catalog and bring host providers toward built-in parity

Partial P1 #13. The provider-per-method macro and the MCP adapter remain; this
removes the blocker they both sit behind and closes the metadata gaps.

**The catalog was frozen at init.** `BridgeCatalog` snapshotted the registry in
`CodeModeAgentTools.init`, so `CapabilityRegistry`'s public post-init
`register(...)` methods were unreachable in the supported flow — and if reached,
would have desynced what search advertises from what execution can invoke. The
registry now carries a generation counter and the catalog rebuilds when it
changes, so the two can no longer disagree. `CodeModeAgentTools.register(provider:)`
exposes this: a host whose domain APIs depend on runtime state — a signed-in
account, a loaded document — can register them when that state arrives, and
search sees them immediately.

**Host providers can express constrained values.** `@CodeMode` rejected any
non-primitive property type, so a host's `allowedStringValues` was always empty
while built-ins advertised theirs — the model had no way to learn a provider's
accepted spellings. An unrecognized simple type is now taken to be a
`CodeModeStringEnum`, exactly as `@BuiltInCodeMode` already assumed, and its
accepted values reach the catalog, the generated TypeScript union, and argument
validation. A denylist of common non-enum types (`Date`, `URL`, `UUID`, …) keeps
the "unsupported property type" diagnostic pointing at the property rather than
letting a natural mistake fail inside generated code.

**Generated metadata is no longer vacuous.** `example` was always
`await path({})` regardless of arguments; it is now a call the model can
pattern-match, with a placeholder per required argument. `tags` was only the
parent path, so `myapp.tasks.complete` was findable only by searching
"myapp.tasks"; every path segment is now a tag.

* Cover the EventKit serialization crashes, pin CI, record what is left

EventKit's serialization logic executed nowhere — not in unit tests, not in CI,
not in evals — because the bridge hard-instantiates `EKEventStore` and the tests
can only reach permission denial. The two implicitly-unwrapped fields that
crashed the execution thread are now covered directly by constructing the model
objects, which needs no permission: an `EKEvent` with no calendar and an
`EKReminder` with no title.

CI runners are pinned to `macos-15` rather than `macos-latest`, so the package's
declared macOS 15 floor cannot drift without a code change.

TODO.md gains a "review follow-up — still open" section listing every part of
REVIEW.md's P1 items that was not completed — the async handler signature and
concurrent Promise.all, native-call interruption, generating the JS bootstrap,
`@CodeModeProvider`/`@CodeModeTool`, the MCP adapter, the remaining bridge store
seams, a simulator job, and the "prompt pending" permission status — so the
finished parts are not mistaken for the whole. It also records that the review's
claim about missing `FetchTaskHandler` redirect and size-cap coverage was stale;
both are covered in NetworkAccessPolicyTests.

* Simplify the review-fix code: dedupe, drop dead code, tighten seams

Quality pass over this branch's changes. No behavior change except one bug the
refactor exposed, noted below.

Reuse:
- One `BridgeInvocationContext.toolError(...)` replaces three separate places
  assembling `CodeModeToolError` from the same three transcript accessors — the
  runtime's `toolError`, `SettlementParameters.error`, and `terminationError`.
  It belongs on the context, which owns those fields.
- One `stringArray(from:evaluating:)` replaces the duplicated
  `JSON.stringify` → decode `[String]` round-trip in `rejectedSuggestions` and
  the timer-error read.
- One `FileSystemBridge.overLimit(...)` replaces three hand-built size-limit
  messages that had already drifted apart in wording.

Simplification:
- `SettlementParameters` bundles the six values `waitForSettlement` and
  `runDueTimers` both needed; the two signatures drop from 7 and 8 parameters to
  2 and 3. `checkInterrupted` replaces the cancellation/termination/deadline
  ladder both were repeating.
- The host-withheld denial branch is hoisted above the `switch` instead of being
  nested identically inside two cases.
- `decodeOutput` checks the watchdog once rather than side by side in a guard's
  else and again after it; its embedded JS returns the in-range value from one
  place instead of two.
- `ExecutionTranscript.record(log:)` now matches the shape of
  `record(diagnostic:)` — one lock/unlock, no branch-local unlocking — and drops
  `droppedLogs`, which was incremented and never read.
- `TypeScriptDeclarations.functionSignature` drops an unused `name:` parameter,
  and `lastComponent(of:)`, which existed only to supply it.
- `CapabilityGrant.Resolution` keeps `withheld: [String]` instead of two sets
  that no caller read except through the accessor that joined them.
- Dropped `CodeModeDate.string(from:)` — never called.

Efficiency:
- `advanceTimers` returns its callbacks' uncaught errors instead of buffering
  them for a second `takeTimerErrors` call, halving the bridge round-trips per
  timer tick.
- The elapsed-time computation reads the clock once through a `Duration`
  extension rather than twice through a two-term attosecond conversion, and
  drops a `max` that could not fire.

Bug found while refactoring: bundling the interrupt checks moved the deadline
check ahead of the settled-state read, which is exactly the spurious-timeout
regression the original comment warned about — a script that fulfilled a hair
past the deadline would have had its result discarded. Ordering restored
(cancellation before the read, deadline after) and pinned by a new test, which
nothing covered before.

* Teach agents the paradigm, not just the API surface

The tool descriptions and the generated TypeScript answer "what is this helper
called and what does it take". Nothing answered "what shape should my work take",
so an agent could reasonably use executeJavaScript as a thin RPC — one call per
operation — which is exactly the pattern this package exists to replace. Every
code example in the package was a *search* example; executeJavaScript had none.

`CodeModeAgentGuidance` supplies the missing half, to pair with
`typeDeclarations()`: one call runs the whole task, filter and aggregate in the
script, return the graded answer rather than the raw data, request only the
capabilities you call.

Three tiers with an optional budget selector, since prompt space is the scarce
resource:
- `.brief` (~160 tokens) — the core idea alone
- `.standard` (~580) — adds the search → write → repair workflow and a worked
  multi-step example
- `.full` (~1000) — adds partial-failure handling, the sequential-native-call
  reality so Promise.all is not over-promised, and the anti-pattern list

`systemPrompt(approximateTokenBudget:)` picks the largest tier that fits. Tiers
are additive — a smaller one loses examples, never a rule, which a test pins by
substring containment. Token counts are estimated at four characters per token
and documented as a planning bound, not a real tokenization. A budget too small
for any tier still returns `.brief` rather than nothing.

Also in executeJavaScript's description: the paradigm now leads instead of the
namespace tour, three worked examples replace having none, and capability
minimization is stated plainly — the eval suite asserts on it 38 times but the
description mentioned it once in passing, so we were grading an unstated rule.

Guarded, because documentation that names a helper the runtime lacks teaches the
exact failure it is trying to prevent: tests check every helper and argument in
both the guidance and the tool description against the live catalog, and run the
worked example end to end. That caught a wrong example on the way in —
`contacts.read` takes `identifiers` (a plural array), so the per-item loop it
showed was the anti-pattern, not the pattern; it is now the example for
"prefer one call that takes a collection".

The new `fs.whole-job-one-script` eval scenario grades the standard rather than
just asserting it: unit tests confirm a transcript splitting one job across three
executions fails on tool order, an over-broad capability list fails even with the
right answer, and the single-script transcript passes.

* Fix CI: iOS/visionOS build breaks and load-sensitive test bounds

Four failures on PR #7, all reproducible locally with the exact CI commands.

**iOS build — a real break in my own CoreLocation fix.** `LocationPermissionDelegate`
crosses an isolation boundary: the manager is created inside a
`DispatchQueue.main.async` block, which is main-actor-isolated on iOS, while
`wait`/`observedStatus` are called from the requesting thread. Swift 6 rejects
sending a non-Sendable delegate across that. It is genuinely thread-safe — all
mutable state is lock-guarded, the handoff is a semaphore — so it is now
`@unchecked Sendable` with the reasoning recorded.

`swift test` on macOS never caught this because `requestLocationPermission` is
inside `#if canImport(CoreLocation) && os(iOS)`, so the macOS build never compiled
the branch. Exactly the gap TODO.md flags about iOS being build-only.

**visionOS build — latent, surfaced by pinning the runner.** `openSystemURL`
calls main-actor-isolated `UIApplication.shared.open` from a nonisolated
synchronous context. This is pre-existing code I did not touch; pinning
`macos-latest` to `macos-15` moved the toolchain to one that diagnoses it. Fixed
with `MainActor.assumeIsolated` on the branch that has already established it is
on the main thread — a hop would return before the open was requested.

**Three load-sensitive test bounds.** Individual tests took 8-9s on the CI runner
against ~0.1s locally, so wall-clock upper bounds written on an idle machine
failed. Each of these is a hang-guard, not a performance assertion, and the
thresholds now say so:
- `setTimeoutActuallyWaitsTheRequestedDelay` keeps its lower bound, which is the
  actual claim (the delay was previously ignored entirely); the upper bound is
  dropped since the script's own 5s timeoutMs already fails a runaway wait.
- The remaining bounds are loosened to stay well under the thing they prove did
  not happen — 20s against a 30s budget, 15s against a 20s timer.
- `completionWaitToleratesALateCallback` waits 60s. The starvation is real:
  parallel tests plus this runtime's thread-blocking timer waits can leave a 0.2s
  dispatch waiting seconds for a GCD worker. That is a property of the
  synchronous bridge model, and one more argument for the async ABI in #9.

Also fixes the `variable 'root' was never mutated` warning CI surfaced in
TypeScriptDeclarations.

Verified locally with the exact CI invocations: `swift test` (322 passing) plus
`xcodebuild -destination generic/platform={iOS,visionOS}`, both succeeding.

* Fire timers in due order, and stop two tests starving on GCD

CI caught a real bug in the timer queue, not just a flake.

`advanceTimers` sorted due timers by registration id alone. That is correct only
when everything came due at the same instant. When the host's sleep overshoots
far enough that two timers with *different* delays land in one tick — which is
routine on a loaded machine — the later one fired first purely because it was
registered first. Timers now sort by due time, using registration order only to
break ties, which is what a real event loop does.

The existing test could not catch this: with delays of 5ms and 10ms it only fails
when the sleep overshoots, so it passed locally and failed on CI. It is joined by
one that reproduces the condition deterministically — delays below the host's
sleep granularity, so both timers reliably come due in a single call — plus one
covering the same-instant tie-break the id sort did get right. Verified by
reverting the fix: the new test fails, the old one still passes.

Separately, `completionWaitReturnsTheDeliveredValue` timed out waiting 5s for an
immediate `DispatchQueue.global().async`. That is thread-pool starvation: the
suite runs in parallel and this runtime's timer waits block GCD workers with
`Thread.sleep`, so a trivial dispatch can wait seconds for a thread. The timeout
is now 60s, since the assertion is that the value arrives rather than how fast.
Worth recording that the starvation is a property of the synchronous bridge
model — the async ABI in #9 is what actually removes it.

* Fresh-look pass: fix two lifetime/concurrency bugs and tighten the rest

A second read of the branch as a reviewer would, rather than as its author.
Two of the findings are correctness bugs in code this branch added.

**Cancel-on-deinit cut off hosts that only iterate events.** The P2 fix made
`JavaScriptExecutionCall` cancel in its `deinit` so a dropped call stops running.
But Swift does not keep a local alive to the end of its scope: a host that reads
`call.events` and never touches `call` again can have it released mid-iteration
in an optimized build, and the deinit then cancelled the execution out from under
the `for await`. The README Quick Start avoids this only because it awaits
`call.result` afterwards. The right semantic is "cancel when nothing can observe
the outcome" — so an `ExecutionObservationToken` is now held by both the call
and the stream's continuation storage, and the execution runs while *either* is
reachable. Two tests discriminate by construction: iterating events after
explicitly releasing the call must see `finished`, and dropping both must free a
single-slot runtime for the next call.

**The concurrency bound blocked the threads it was protecting.** The slot
semaphore was acquired inside `executionQueue.async`, so every execution beyond
the limit held a GCD worker while waiting — exactly the resource the limit exists
to conserve. `ExecutionSlots` is an actor; waiters park as suspended tasks, a
freed slot hands directly to the next waiter, and a call cancelled while parked
throws before anything is dispatched. Tested: a call cancelled while waiting
reports CANCELLED and never ran (the file it would have written is absent).

**The timer loop polled.** `runDueTimers` slept in 5ms slices — 200 wakeups a
second per sleeping execution, and up to 5ms of cancellation latency — which is
what made CI's thread starvation visible. `ExecutionCancellationController` now
owns an `NSCondition`: one interruptible wait until the timer is due or the
deadline passes, woken immediately by `cancel()`. The wall-clock `Date` is only
the wake-up hint; the loop still re-checks against `ContinuousClock`, so an NTP
adjustment cannot move either the timer or the deadline.

**Smaller findings:**
- The per-capability `dts` flattened `apple.fs.read` to `declare function
  apple_fs_read`, a name that does not exist. It is now declared at its real call
  path; bare globals like `fetch` are declared directly.
- `health.permission.request` changed its result shape in the P2 commit but its
  advertised `resultSummary` still promised a `granted` field. Golden regenerated.
- `HostConfigurationValidator.validate(configuration:)` warns when
  `capabilityGrant` is `.unrestricted`, and the README Quick Start — the thing
  that gets copy-pasted — now models a grant instead of the unenforced default.
- `hostWithheldCapabilityIdentifiers` was public API for internal bookkeeping.
- `ExecutionLimits` is documented as bounding concurrency too, not just "a single
  execution", since `maxConcurrentExecutions` lives there.
- `CodeModeAgentGuidance.Length` drops `Comparable` and a private ordering it
  carried only so the budget selector could sort; `allCases` already is the order.

Verified with the exact CI invocations: `swift test` (331 passing) and
`xcodebuild -destination generic/platform={iOS,visionOS}`.

* Synchronize the sleep-interrupt test on the sleeper actually starting

The test cancelled 50ms after *dispatching* the sleeper block. On a starved CI
runner the dispatch alone can take seconds, so the cancel arrived before there
was anything to wake, the sleeper only ran after the test had given up, and the
failure read as "cancel did not wake the sleep" when the sleep had never begun.

It now waits (generously) for the block to signal that it is about to sleep,
then cancels and measures only the wake-up — which is the property under test.
If the cancel lands in the window before the wait starts, `sleep(until:)` sees
the flag on its first check and returns immediately, so there is no hang and no
false positive.

* Stop the test suite from starving itself on CI

The last CI run failed four tests at ~66 seconds each — including two that need
nothing but a single GCD thread. That is a runner-wide stall, and the suite was
partly causing it: seven watchdog tests each spin a core at 100% for their
budget, and a dozen event-loop tests each hold a GCD worker for the length of a
timer, all dispatched in parallel onto a three-core runner. Serializing those
three suites keeps them from stacking on each other; cross-suite parallelism is
unchanged.

Two tests were also asserting more than their property, which is why a stall
read as a runtime bug:

- `executeCancelsWhenAwaitingTaskIsCancelled` cancelled after a `Task.yield()`.
  Under a stall the test task can be descheduled past the script's 20s timer,
  and cancelling a finished execution is a no-op — reported here as the script
  "ignoring" cancellation. It now cancels only after observing the script's own
  `running` log on the events stream, which makes the outcome CANCELLED
  regardless of scheduling.
- `anUnsettleablePromiseIsReportedImmediately` and
  `aTimerStillPendingAtTheDeadlineTimesOut` carried wall-clock bounds that their
  error codes already proved: JS_RUNTIME_ERROR rather than EXECUTION_TIMEOUT
  shows the 30s budget was not run out, and EXECUTION_TIMEOUT rather than a
  returned `1` shows the 30s timer was not waited out. Dropped.

No product code changed. Run locally: 331 passing.

* Declare CodeMode as a direct dependency of the authoring tests

`CodeModeAuthoringTests` uses `CodeModeConfiguration` and `CodeModeAgentTools`
but declared only `CodeModeAuthoring` and `CodeModeMacros`, reaching `CodeMode`'s
symbols through re-export. SwiftPM did not treat that as an edge for rebuild
invalidation, so whenever a `CodeMode` type changed layout the authoring test
objects went stale — and a plain `swift test` then either failed to link
("Undefined symbols: CodeModeConfiguration.init(...)") or crashed with signal 11
partway through the run. Every such failure this branch hit was worked around by
touching the test sources; this is the fix.

Verified by reproducing the trigger: add a stored property to
`CodeModeConfiguration`, run `swift test` with no workaround. Before: link
failure or segfault. After: the authoring tests rebuild and all 331 pass.

* Make the timer tests deterministic with an injectable clock

The timer tests were the least reliable tests in the suite, and the earlier
fixes — serializing suites, widening bounds — reduced the failure rate without
removing the cause: they slept real time and asserted wall-clock bounds, so a
loaded CI runner turned a 150ms wait into seconds and every assertion became a
guess about how slow the machine was allowed to be.

`RuntimeClock` is now the runtime's source of time for the two places that wait:
the timer loop and the watchdog deadline. `RealClock` is production and
unchanged. `VirtualClock` makes `sleep(until:)` a jump, so under test a timer
fires instantly and exactly, and a test can assert on how long the runtime
*asked* to wait rather than on how long the machine took:

- `setTimeoutActuallyWaitsTheRequestedDelay` asserts `clock.elapsed ==
  .milliseconds(150)` — exact, where it previously asserted `>= 0.14` real
  seconds with no upper bound it could safely hold.
- `aTimerStillPendingAtTheDeadlineTimesOut` asserts it stopped at exactly 100ms,
  never anywhere near the 30s timer.
- `anUnsettleablePromiseIsReportedImmediately` asserts `elapsed == .zero` — the
  runtime never slept at all.
- `aResultThatSettlesRightAtTheDeadlineIsNotDiscarded` was a 12-iteration race
  hoping to land a timer on the deadline; it is now one exact case with timer
  and deadline at the same instant.

`VirtualClock(overshoot:)` models a slow machine precisely — every sleep wakes
late by a fixed amount. That matters for `timersComingDueInOneTickStillFireInDueOrder`:
after the earlier switch from 5ms polling to an interruptible wait, real sleeps
stopped overshooting enough to bring two timers due in one tick, so that test
had quietly stopped exercising the condition it exists for. With a 10ms overshoot
it reproduces it on every run.

Both converted regression tests were mutation-checked: the overshoot test fails
against the id-only sort, and the exact-deadline test fails against a
deadline-before-settled-state check — the two bugs they guard.

Kept on the real clock deliberately: watchdog termination of a CPU-bound script
(driven by JavaScriptCore's own execution-time callback, which virtual time cannot
advance) and the cancel-mid-sleep tests, which are already outcome-deterministic
because they synchronize on observable events rather than durations.

The seam is internal — `CodeModeAgentTools.init(config:clock:)` is not public.
Production time is not a host decision. Verified with the exact CI invocations:
`swift test` (331 passing) and `xcodebuild -destination generic/platform={iOS,visionOS}`.

* Close the source side of fs.move/fs.copy, and make overwrite non-destructive

The P0 #4 fix guarded the destination against sandbox roots but never checked
the source. `apple.fs.move({ from: 'documents:', to: 'tmp:stolen' })` succeeded
and moved the user's whole Documents directory into tmp:, which the OS may
purge; `fs.copy` from a root duplicated the entire tree with no size bound.
Both sides are now refused, matching fs.delete.

The overwrite path also removed the existing destination *before* the move or
copy ran, so any failure after that point lost it:
- a missing source with overwrite: true deleted the destination, then threw;
- `fs.move({ from: 'tmp:x', to: 'tmp:x', overwrite: true })` deleted x itself;
- a full disk or permissions error mid-copy did the same.

The destination is now moved aside (a same-directory rename), the operation
runs, and only on success is the old item removed; on failure it is moved back.
Validation also runs first: the source must exist, and the destination may not be
the source or a path inside it.

`fs.copy` now answers to `maxWriteBytes` — it writes new bytes, and was otherwise
a way around the write limit. Directory sizes are walked with an early exit, so a
huge tree is refused without being traversed in full.

Tests: both root-source cases, missing-source overwrite, self-overwrite,
destination-inside-source, a copy over the limit made of individually small
files, and a filesystem whose copy fails after the aside move — the destination
must come back intact with no aside file left behind.

* Render TypeScript declarations as object types so reserved words are legal

The generated declarations used `declare namespace`, whose members are
declarations and need identifiers. Helpers named with reserved words —
`apple.keychain.delete`, `apple.photos.export`, `apple.documents.export` —
rendered as `function delete(…)` and `function export(…)`, which is not valid
TypeScript. Any host that type-checks the output failed on it.

Roots now render as `declare const apple: { keychain: { delete(args: …): …; }; };`.
Object type members may be any property name, and the shape reads the same to a
model. Each per-capability fragment is valid on its own; `surface(for:)` remains
the way to get one compilation unit covering several capabilities, since it
merges them under a single declaration per root.

The new test checks the whole iOS surface against the full ECMAScript reserved
word list. Verified against a real compiler would be better still, but the local
`tsc` shim points at an uninstalled TypeScript, so that check is left for CI or
a machine with a working install.

* Stop the agent docs from spending tokens hosts can't budget

Two places the documentation work undercut its own token budgeting.

The `executeJavaScript` description had grown from 2,711 to 5,802 characters,
most of it three worked examples. Tool descriptions go out on every turn and a
host cannot trim them — which is exactly why `CodeModeAgentGuidance` has budgeted
tiers. The examples now live only there; the description is 4,656 characters, the
remainder over main being the paradigm sentence, the concurrency model, and the
diagnostics guide. The one rule the examples carried that the guidance lacked —
check for an argument that takes a collection before writing a loop of single
calls — moves into the guidance workflow.

`typeDeclarations()` returned the whole platform surface, roughly 21,000 tokens
on iOS, while the docs paired it with a ~580-token guidance tier. It now follows
the host's `CapabilityGrant`: a host granting three helpers gets about 1,000
tokens, most of it the shared preamble, and never advertises a helper the model
would be denied. `typeDeclarations(for:)` takes an explicit subset for when even
the grant is too broad. `CapabilityGrant.permits(_:)` / `permits(key:)` back both.

Also corrects the docs' claim that over-broad capability lists are "refused":
with a ceiling, the extra capability is withheld and the run continues with a
warning. The guidance now says what is true — it widens the grant for nothing.

Tests: a parser over every `apple.*({ … })` call in the description and all
guidance tiers checks each helper and argument against the live catalog, so new
examples are covered without updating a list; a size guard stops the description
regrowing examples; and declarations are checked to narrow with a grant, narrow
to an explicit subset, and cover everything when unrestricted.

* Decode JavaScriptAPIReference without a dts key

Adding `dts` as a non-optional stored property made the synthesized decoder
require it, so a reference encoded before this branch — a host's cached search
results, an eval fixture — failed to decode with `keyNotFound: dts`.

`dts` is now optional on decode, and when it is absent the declaration is
regenerated from the decoded fields, so a legacy reference comes back with the
same declaration a fresh one would carry rather than an empty string. Encoding is
unchanged.

Tests: the exact legacy shape decodes and gains a generated declaration, and the
full live catalog round-trips through Codable unchanged.

* Require PathPolicy.allowedRoots instead of defaulting it to empty

The root guards on fs.move, fs.copy, and fs.delete can only recognize a root the
policy names, and `allowedRoots` defaulted to `[]`. A host with its own
`PathPolicy` therefore got none of the root protection — silently, with
everything compiling and the guards never firing. That is a fail-open default on
a safety check.

The requirement now has no default, so a custom policy has to state its roots;
one that genuinely has none to protect can return `[]` explicitly. This is a
source break for custom conformers, intentionally: pre-1.0, and the alternative
is a protection that quietly does nothing. `isAllowedRoot` keeps its default.

Test: a host-style policy narrowing the default to two roots gets both the
source- and destination-side root refusals, and the file it would have moved
survives. README notes the requirement for hosts.

* Give search its own slots, and drop a dead branch from ExecutionSlots

Search shared the execution slots, so a host running long scripts at its
concurrency limit stalled API discovery behind them — exactly when an agent is
working out its next step. Search is cheap, capability-free, and bounded to 2s;
it now has its own slot pool of the same size.

`ExecutionSlots.withdraw` recorded ids it could not find "for later", on the
theory that cancellation might beat the waiter into the queue. It cannot:
`acquire()` is actor-isolated and parks the waiter synchronously, before any
`withdraw` task from the cancellation handler can run on the actor. The only way
to reach that branch was after `release()` had already handed the waiter a slot
— and then the id was inserted and never removed. The branch is gone; a late
cancel is a no-op, and the execution sees it through its cancellation controller.

Test: with one execution slot held by a script that writes a file after 3s, a
search returns before the file exists. The occupant is synchronized on its own
`running` log rather than a sleep.

* Bring TODO.md and the README's API list up to date

TODO.md still described the concurrency bound as "a semaphore acquired *on* the
worker" — the design this branch replaced because it blocked the threads it was
protecting — and listed `runOnExecutionQueue` cancellation as "NOT addressed",
which it now is at every stage. Both entries describe the current mechanism and
name the tests that cover them.

The README's Public API list predated every public type this branch added:
`CapabilityGrant`, `ExecutionLimits`, `FileSystemLimits`, `CodeModeAgentGuidance`,
`TypeScriptDeclarations`, and the new `CodeModeAgentTools` methods. It now lists
them, grouped by where a host meets them.

* Verify the watchdog on iOS, and make the suite honest about the keychain

TODO.md has carried one pre-tag item since the start: JSC ships per-OS, and the
watchdog had only ever been verified on macOS. The full CodeModeTests target now
runs on an iPhone 16 Pro simulator (iOS 18.6) — the first time this suite has
executed on iOS at all — and all seven watchdog tests pass there: CPU loop, loop
in a promise chain, catch-proof termination, cancel mid-loop, runaway getter,
serialization budget, and search. 315 tests pass.

That run also failed six tests, all keychain, all with -34018
(`errSecMissingEntitlement`): an unsigned SwiftPM test bundle on the simulator
has no keychain access group. An environment limit, not a bug — but it exposed
two real problems:

- The bridge reported "keychain.write failed with status -34018", which tells
  neither the model nor the host developer anything. Failures now carry
  Security's own description of the status, and -34018 specifically says the
  host app lacks a keychain entitlement and that retrying will not help. Host
  developers hit exactly this in their own unsigned test targets.
- The tests could not tell "no keychain here" from "keychain broken". Tests
  whose subject is keychain storage now skip, with that reason, when a probe
  shows the entitlement is missing. The capability-gating test only touched the
  keychain incidentally, so it now asserts its actual subject — the call was not
  denied — and runs everywhere.

On macOS every keychain test still runs and passes; on the iOS simulator exactly
the four storage tests skip and the rest pass. Simulator, not device.

* Correct what the declaration docs claim, now that tsc has checked it

With a working TypeScript compiler (7.0.2) the generated declarations were
checked for real rather than by proxy:

- the whole surface for iOS, macOS, and visionOS each compile with zero errors
  under `tsc --strict`;
- all 121 per-capability fragments compile when paired with the preamble.

So the object-type rendering holds up, including the reserved-word helpers. But
the doc comment on `declaration(for:)` claimed each fragment was "valid
TypeScript on its own", and the compiler disagrees on two counts: a fragment
references `CodeModeValue`, which only the preamble defines, and two fragments
for the same root each declare it, so joined fragments do not compile as one
unit. Neither is a defect — a model reading search results is unaffected, and
`surface(for:)` / `typeDeclarations(for:)` already exist for compiling several
capabilities together — but the comment now says exactly that instead of the
stronger claim. Doc-only change.

* Compile the generated TypeScript declarations in CI

The declarations go into model prompts and into hosts' type-checkers, so whether
they are valid TypeScript should be checked by a compiler, not inferred. The
Swift tests only catch failure shapes someone already thought of — the
reserved-word test exists because `function delete(` shipped once.

`scripts/check-typescript-declarations.sh` writes every declaration the
generator produces — the preamble, the unrestricted surface for iOS, macOS, and
visionOS, and all 121 per-capability fragments — then compiles them with
`tsc --strict`, TypeScript pinned to 7.0.2. It runs the same way locally
(`TSC=tsc` to use an installed compiler) and in CI.

Everything compiles in one pass rather than 124. The preamble stays a global
script, as it is in a host prompt; each surface and fragment becomes its own
module, so their top-level `declare const apple` stay local instead of
colliding, and each is checked exactly as it would be used alone.

The script refuses to pass vacuously: it fails if the dump produced fewer than 3
surfaces or 100 fragments, or if tsc would check fewer files than were written —
an empty compilation succeeds, so a filter typo would otherwise go green.

The dump is a Swift test that is inert unless `CODEMODE_DTS_OUTPUT` is set, so
`swift test` is unchanged. In CI it runs right after the test step, when the
build is already warm.

Verified both ways: all 125 files compile clean, and reintroducing the original
`function delete(` bug makes the script exit non-zero with 422 compiler errors.

* Bound timer delays before converting them, so a script can't crash the host

Found by Codex review. The timer loop converted the delay it read from
JavaScript with `Int(delayMs.rounded(.up))`, and `Int(_: Double)` traps on
anything non-finite or out of range. A capability-free
`await new Promise(r => setTimeout(r, 1e300))` — or `Infinity` — killed the
embedding app with "Double value cannot be converted to Int". Search runs the
same loop, so it was reachable with no capabilities at all. This is the exact
bug class P0 #3 removed everywhere else, reintroduced in the timer loop.

The real fix is on the Swift side: the wait is bounded by the time remaining
before the deadline *before* any conversion, so whatever arrives — 1e300,
Infinity, NaN — the converted value is at most the remaining budget, which is
always small. A huge timer now ends in an ordinary timeout, exactly at the
deadline.

The JavaScript side also normalizes delays, but that is hygiene, not a
boundary: `__codemode` lives on globalThis, so a script can replace
`nextTimerDelay` or push a timer entry directly and skip it. NaN, negative, and
missing delays fire as soon as possible, as on the web; anything above 2^31-1 ms
is clamped to it (browsers wrap such delays to fire immediately, which would
turn `setTimeout(r, Infinity)` into a hot loop).

Tests, under the virtual clock so each is exact and instant: unrepresentable
delays time out at precisely the 100ms deadline; degenerate delays fire with zero
elapsed; search survives 1e300; and three tampering scripts that bypass the
JavaScript normalization entirely — replacing `nextTimerDelay`, or pushing an
Infinity entry — still end in a timeout at the deadline rather than a crash.

* Count hidden entries against the fs.copy limit

Found by Codex review. The copy-limit walk listed directories through
`LocalCodeModeFileSystem.listDirectory`, which passed `.skipsHiddenFiles`, while
`FileManager.copyItem` copies everything. A 1,024-byte `.hidden` file copied
successfully under a 4-byte limit, and a hidden file or subtree of any size
could pass the default 16 MiB ceiling the same way.

The root cause was a display choice living in the storage layer: hiding
dotfiles is what `fs.list` wants to show a model, not what a filesystem
abstraction should report. `listDirectory` now returns every entry, marking
hidden ones with a new `CodeModeFileSystemEntry.isHidden`, and `fs.list` filters
on that flag itself — so quota accounting sees everything while listings are
unchanged. `isHidden` comes from the filesystem's own `isHidden` resource value,
the same test `.skipsHiddenFiles` applied (dot-prefixed names plus the hidden
flag), so `fs.list` hides exactly what it hid before.

`isHidden` defaults to false, so existing code constructing entries still
compiles. The `listDirectory` requirement now documents that it must include
hidden entries; a custom `CodeModeFileSystem` that omits them would under-count
the same way. That contract cannot be enforced at compile time, so it is stated
where a conformer will read it.

Tests: the reviewer's exact reproduction is refused; a hidden *directory*
holding a large file is counted; fs.list still shows only visible entries while
the storage layer reports the hidden one, marked.

* Validate exception line numbers, so a script can't crash the host with one

User code is spliced into an `(async function(){ … })()` wrapper, so a
script can close it early and throw an arbitrary object at top level.
The host read that object's `line` through `NSNumber.intValue`, which
saturates -Infinity to Int.min, and the line adjustment then overflowed:
`throw { line: -Infinity }` trapped, with no capabilities granted.

Only a positive whole number in a plausible range is now accepted as a
line or column, and the adjustment itself can no longer overflow.
Pre-existing on main; found sweeping the other JS-to-Swift numeric
reads after the timer-delay crash.

* Mark the pre-merge verification done in TODO.md

The iOS simulator run closed the last open item, but the heading was still
half-checked and a parenthetical still said iOS was compile-verified only.
visionOS genuinely is, and now says so on its own.

* Compile scripts on their own, so they can't break out of the harness

User code was spliced as text into `(async function(){ … })()`, so
`return 1; })(); …; (async function(){` closed the wrapper and ran at
top level, outside the harness's `.catch`. That is how a thrown
`{ line: -Infinity }` reached the host and crashed it; the previous
commit made the line read safe, this removes the way in. Search had the
same shape: its expression was pasted into `const __search = (…)`.

Both now hand the source over in a global and compile it with the
`Function`/`AsyncFunction` constructors, which parse a body on its own,
so it cannot close the function it is compiled into — a body that tries
is a syntax error. A search expression can still close its own
parentheses, but only into a function body it could write anyway as an
async arrow.

Syntax errors keep accurate lines (JavaScriptCore numbers the generated
`function anonymous(\n) {\n` source, so the offset is 2 for both paths).
They no longer carry a column: JSC reports the column of the constructor
call, not the error, and the old column was off by the wrapper's
indentation anyway. The agent guidance stopped promising one.

* Rewrite the README as an overview, at about a third of the length

It had grown into an accumulated reference: no explanation of how a call
flows, the capability grant explained three times, a dump of the public
API, and eval CLI flags that EVALS.md already covers. It now runs: what
Code Mode is and why, install, quick start, how it works, wiring it into
an agent, the security model, custom helpers, host setup, development.

Dropped: the public API list, the search interface listing and event
cases (the Swift types document both), the eval tolerance flags (in
EVALS.md), and the stale "Shipped Expanded Families" / "Deferred in v1"
sections. Added: a how-it-works walkthrough, the `@CodeMode` macro, which
the README never mentioned, and the Info.plist keys as a table.

Corrected against the code: `approximateTokenBudget: 400` selects
`.brief`, not `.standard`; `.standard` is ~620 tokens now; there are 52
eval scenarios, not 49; and syntax errors no longer carry a column.
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