docs(client): Agent Skills — close out the security review's SDK-side remainder - #66
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… remainder The four items left open in the response to the Agent Skills security design review. Three are documentation, one is tests; no behavior changes, and the code halves of rows 9 and 2 are deliberately untouched. **Privilege separation** (row 9 docs half, and the agreed counter-proposal for row 26). The recommended deployment runs the reconcile as a different identity than the agent, which is the whole reason the ``0644``/``0755`` modes deny anything: the agent reads its instructions and cannot rewrite them, or the manifest. That is the mitigation for AZ-1, a prompt-injected agent editing its own skills. Write access to the manifest is the worse half — it is what tells the *next* reconcile which paths the SDK may delete — which is why ``_prune`` re-validates every entry from scratch rather than trusting it. The README documents the pattern and hands the operator the check to run, because the SDK cannot run it: it knows only its own identity, which trivially has write access, having just written there. So ``ReconcileReport`` grows no writability field — the review asked for one and we declined, since any check the SDK could make would answer a different question than the one asked and manufacture false confidence exactly where caution is wanted. ``agents.md`` records that reasoning so the field is not added later by someone reading its absence as an oversight. **Three hostile-manifest prune tests** (row 12 remainder): a well-formed manifest listing ``/etc/passwd``, ``../../../etc/passwd``, and a path under a parent that has since become a symlink. ``_prune`` already refuses all three, so these turn asserted into verified. Two things make them worth more than their line count. They are deliberately *well-formed* — the corrupt-manifest suite above them proves nothing here, because a corrupt manifest suppresses every destructive action wholesale, whereas these manifests give the implementation everything it needs to prune. And "deleted nothing" is asserted through an unlink spy rather than by checking that ``/etc/passwd`` still exists: the test process cannot delete that file anyway, so the obvious assertion would pass against an implementation with no path check at all. **One sentence on** ``"*"`` (row 16 remainder). It materializes the whole project library, so every skill's ``description`` enters the agent's context — including skills no AI Config references and skills belonging to other teams. **The Windows platform bound is now explicit** (row 2 residual), in ``safe_fs.py``, ``agents.md`` and the README. Reparse-point checks (``GetFileAttributesW`` / ``FILE_FLAG_OPEN_REPARSE_POINT``) are not implemented, by decision: Windows is not a supported or tested platform for this release, neither repository has a Windows CI runner so the checks would ship unverified, and the TypeScript SDK could not match them in any case because Node exposes no ``*at()`` family on *any* platform. Implementing them in Python alone would break cross-language parity and trade a documented bound for an unverified one. Two consequences are recorded rather than left to be rediscovered: on Windows, write permission on the managed root is the only boundary, which is what makes privilege separation the mitigation and not merely advice; and this retroactively lowers the priority of the row 25 reserved-device-name work, noted where that code lives. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
write_skills is a one-shot reconcile, so a revocation takes effect at the next process restart. watch_skills runs that reconcile now and again whenever the configured store reports a change, so a revoked skill's files leave the disk within a debounce interval of the store learning about it. It is wired to the SkillStore interface, not to any one transport: it needs a store that implements add_listener and nothing more, and refuses loudly when the store does not, since a watcher that silently never fires looks exactly like one whose skills never changed. Above the interface, remove_listener joins add_listener as the optional second half of change notification, on the SkillStore contract and on InMemorySkillStore. SkillWatcher.close needs it to detach; without it a store held every watcher ever created for the rest of its life. The watcher probes for it, so a store without it keeps working. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
…network The half of the delivery transport that has no I/O: identifying a skill object on the wire by kind inline-resource plus category skill, translating it into the raw object shape the SkillStore interface defines, holding it by (key, objectVersion), and applying a payload's events as one commit at payload-transferred. The store that puts a connection underneath this follows separately, so the three decisions that matter most can be reviewed on their own: - objectVersion is the skill's version; version is the payload's. The translation happens in one place and TestVersionTranslation asserts it in both directions, because confusing them fails silently. - Changes commit at payload-transferred, not per object. A half-applied full transfer would briefly empty the store, which with pruning on is the difference between a reconcile and deleting a customer's files. - A hashless object is held, not dropped, so verification withholds it with a reason code rather than the transport reporting it absent. Flag and segment objects share the connection and are skipped and counted, not rejected. Nothing here is exported yet; the store exports it. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
…oncile watch_skills awaited write_skills and only then constructed SkillWatcher, which is where the store listener attaches. The reconcile snapshots the store as its first step and then spends the rest of its time on the filesystem, so every write, fsync, prune and manifest rewrite in that first pass ran with nothing listening. A change delivered in that window was never seen, and since nothing re-reconciles on a timer, a revocation that landed there waited for the next unrelated change — on a quiet root, the next restart. Exactly the gap watch_skills exists to close. The watcher now attaches its listener before the initial reconcile and starts its worker after. notify only sets an event, so a change arriving mid-reconcile is recorded and picked up by the worker's first pass, while holding the thread back keeps write_skills's one-root-one-reconcile contract: the worker cannot race the caller's own reconcile over the same manifest. A reconcile that raises detaches the listener on the way out, since the caller is handed an exception rather than a watcher to close. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
The protocol reader took payloads[0]'s intentCode and applied it to the skill object set, which is what the delivery protocol requires — one payload per credential, read the first intent, tolerate the rest — but it left the assumption behind that rule undocumented and unguarded. If the one-payload guarantee ever widens, an xfer-full for another payload would start an empty pending set and the next payload-transferred would publish it: every skill reported revoked, and with pruning on, a customer's files deleted. The first payload is still the payload that is read. What is new is that the reader now knows which payload skills actually arrive on — learnt from the intent's id, or from the (p:<id>:<version>) selector, since no object or transfer event carries a payload id of its own — and declines to apply a transfer of any other, holding last known good, warning once, and counting it in diagnostics.payloads_ignored. An intent describing more than one payload warns once on its own, because that is the one case the comparison cannot catch: another payload's transfer arriving before any skill has been seen has nothing to be compared against. Behaviour under one-payload delivery is unchanged, and a full transfer of the skill payload still empties it — every skill deleted is a real state the guard must not mask. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
The SDK-facing FDv2 channel now delivers skills the way streamer #4681 and gonfalon #70638 spell them: object kinds are open strings, the agent-skill payload is classified `generic`, and every generic object carries only `key`, `kind`, `version` and `object`, exactly like a flag. A skill arrives under kind `skill` with its own version folded into the key as `<key>:<version>`. There is no `category` field and no `objectVersion` field; both came from an earlier streamer draft that never shipped. Identification is now the kind alone. The wire key is split in one place, `_split_wire_key`, and both the put and the delete translation go through it. A key that will not split cleanly is held rather than dropped — version-less, or with the offending text as its version — so verification withholds it with `invalid_version` under a key the caller recognises; only a key with nothing before the delimiter is dropped, since there is no identity to hold it under. `SDK_DATA_MODEL_VERSION` goes with it: the connection's `mv` parameter only accepts flag model versions, and generic payloads ignore it. The transport stops sending it in the following change. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
FDv2SkillStore puts LaunchDarkly's SDK-facing FDv2 channel underneath the protocol layer: GET /sdk/poll and GET /sdk/stream, authenticated with the environment's server-side SDK key, streaming by default. It carries basis across requests, sends If-None-Match and treats 304 as a current answer, retries with capped jittered backoff, honours Retry-After only up to max_backoff, gives up after a bounded run of consecutive failures where a committed payload resets the count, and keeps serving last known good through every failure. A mobile key or client-side environment ID is refused in the constructor. Standard library only. close interrupts the socket rather than only setting a flag, because the delivery thread lives in a read no flag can reach; without that every shutdown of a healthy stream waited out the full join timeout. The no-store message now names FDv2SkillStore first, and watch_skills points at it as the store with a delivery transport. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
_Requester.stream wrapped only the connect as recoverable, so a read timeout, reset or truncated chunk in the body reached the delivery loop as whatever the socket raised. The loop read that as a bug and gave up: delivery stopped for the process lifetime, taking updates and revocations with it, the first time a socket died. read_timeout exists to bound a stream that has gone quiet so the loop can reconnect, and tripping it did the opposite. The body now carries the same promise the connect already did. Wrapping the line source rather than the whole read keeps protocol reader errors out of it: those are raised from the consumer's loop body, where they still surface as the bugs they are. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
…n promptly Three faults in the delivery loop, all of which left the store reporting itself healthy while doing less than it claimed. **An up-to-date stream tripped the failure cap.** The consecutive-failure count reset only at a commit, and an environment whose skills are not changing answers every reconnect with `intentCode: "none"` and transfers nothing. A stream only ever ends by being dropped, so each recycle of a perfectly healthy idle connection counted as a failure — announced with a `goodbye` or not — and `max_consecutive_failures + 1` of them stopped delivery for the process lifetime, revocations included. The reset on commit covered only the case where content had changed, which is the case that was easy to test and not the case that runs in production. `_TransferOutcome` now reports `up_to_date`, and a complete answer that transfers nothing breaks the row of failures exactly as a commit does. An intent this module does not recognise is still not an answer. **`close` could not interrupt a poll.** The interrupt reached the streaming connection only, so polling parked in its request with nothing to reach and `close` returned when its join timed out — on a 300s-class request, long after the process meant to exit. `_Requester` now tracks the response of a poll in flight and offers `interrupt`, which `close` calls alongside the stream's own. A request still inside its connect has no response to reach; that one is bounded by `read_timeout`, and `start` no longer leaves the store inert when a join times out around it. An interrupt we asked for is no longer recorded as a delivery failure. **`close` left a waiter parked.** `wait_for_skills` waited on the first payload alone, so a shutdown racing a waiter added the waiter's whole timeout to it. Delivery ending is now its own event: a waiter is released by a payload, a give-up or a close, and reports whether a payload actually arrived rather than merely that it was let go. That also settles what `_give_up` had been quietly asserting — it set the first-payload flag to unblock waiters, which made `wait_for_skills` answer `True` for a store holding nothing. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
A stream only ever ends by being dropped, and LaunchDarkly — and any proxy in between — recycles a long-lived one. Every reconnect therefore logged "Skill delivery failed" at WARNING, for as long as the process ran. Until the previous commit that noise was bounded, because an idle stream gave up after eleven recycles and went quiet; now that delivery correctly survives them, it would run forever and describe a healthy store as failing. A connection that got a complete answer before it ended — a committed payload, or an up-to-date intent — delivered everything it was asked for, so its reconnect is now DEBUG and says so. A connection that ended without answering is the case the warning exists for and still gets it: a connect that never landed, or a transfer that died part-way through. Filling a customer's logs with a fault they do not have is not merely untidy; it teaches them that the level which means something can be ignored. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
andrewklatzke
approved these changes
Sep 14, 2026
Stacked on the protocol-layer PR (`xie/skills-fdv2-protocol`). Third of three PRs split out of #69, and the one that makes the feature real: the network underneath the protocol reader, exported as `FDv2SkillStore`. ## Why this shape Skill content arrives over `GET /sdk/poll` and `GET /sdk/stream`, authenticated with the environment's server-side SDK key. These are the SDK-facing endpoints the base SDK's FDv2 data source uses, and the channel that payload signing will eventually cover. No private route is involved, and no credential other than the environment's own SDK key ships to a customer host. Standard library only, so the content path adds no dependency to a package whose sole runtime dependency is `opentelemetry-api`. ## What's here **`FDv2SkillStore`.** Authenticates, streams (default) or polls, carries `basis` across requests, sends `If-None-Match` and treats 304 as a first-class current answer, and serves `get_object` / `all_objects` / `add_listener` / `remove_listener` from what the protocol reader has committed. Capped jittered backoff; `Retry-After` honoured but clamped to `max_backoff` and rejected when non-finite; bounded consecutive-failure retries, where a committed payload resets the count. One network timeout, `read_timeout`, whose default follows the mode: 10s for a whole poll, 300s between reads on a stream. A mobile key or client-side environment ID raises from the constructor. Last known good survives every failure; `diagnostics` and `failed` report the degradation. **`close` interrupts the socket.** The delivery thread parks in a read no flag can reach, and closing a urllib response from another thread does not unblock CPython's buffered reader, so `_interrupt_read` shuts the socket down underneath it. Without that every shutdown of a *healthy* stream blocked for the full join timeout. **Above the interface**, two strings: `NO_STORE_MESSAGE` now names `FDv2SkillStore` first, since it is the first thing a user sees on a missing store and offering only the development store was wrong once a production transport existed; and `watch_skills`' refusal message names it as the store with a delivery transport. ## Bugs found and fixed while testing the loop Five, all sharing one shape: the store stopped delivering while continuing to report itself healthy. - **The consecutive-failure counter never reset in stream mode.** `_stream_once` always ends by raising, so a reset on return was unreachable and `failures` grew for the whole process lifetime. Eleven *fully successful* payload transfers were enough to trip `max_consecutive_failures` and stop delivery for good, revocations included. A commit now resets the count, in `_apply`. - **A non-finite `Retry-After` killed the delivery thread.** `float("inf")` parses, and `Event.wait(inf)` raises `OverflowError` from inside the recoverable-error handler. Non-finite values are rejected and every honoured delay is clamped to `max_backoff`. - **`close()` during the initial connect waited out its full join timeout.** `self._connection` was assigned after the connect returned, so a `close()` in that window found nothing to interrupt. The stop flag is re-checked immediately after the assignment. - **`close()` blocked for the full join timeout on every healthy stream.** See `_interrupt_read` above. - **A stream interrupted by our own `close` was reported as a delivery failure.** Also: `connect_timeout` was accepted and never used, so a poll against a black-holed host hung for 300s rather than 10. It is gone, with the request timeout now chosen by mode, and `TestTimeouts` measures the bound against a socket that accepts and never answers. ## Tests > **Rebase note.** The previous push of this branch had silently reverted the protocol PR's last commit (payload identity: `payloads_ignored`, `_is_foreign_payload`, `TestPayloadIdentity`). Rebasing onto the updated protocol branch restored it; the full suite passes with it present. `_FakeFDv2Endpoint` is an in-process `ThreadingHTTPServer` implementing the wire contract, so request construction and header handling are exercised over real sockets rather than mocked. Covers skill put/delete over the wire, mixed payloads, 304, `basis` round-tripping, reconnect/backoff in both modes, `Retry-After` including non-finite and oversized values, bounded retries and the reset on commit, prompt shutdown during connect and during a healthy stream, hashless envelopes end to end through the accessors, server-side-only credentials, timeouts, and `watch_skills` over the transport: a wire-level revocation pruning a file without a restart. Full suite 1629 passing, 11 skipped; `ruff`, `ruff format`, and `mypy` clean. ## Open items, none in this PR's scope - 🔴 **`contentHash` is not on the wire yet.** Against a real environment today every skill resolves to nothing. This PR makes that loud (an error per hashless object, a summary per wholly-hashless payload, `diagnostics.hashless_objects`) rather than surviving it. - 🔴 **Server-side skill delivery is not deployed.** The wire shape this store reads — kind `skill`, key `<key>:<version>`, generic payload — is what [streamer #4681](launchdarkly/streamer#4681) and [gonfalon #70638](launchdarkly/gonfalon#70638) emit; both are still open. No account can receive skill objects until they ship and the producer is enabled. - 🟡 **FDv2 is opt-in per account.** A real environment returns 403 today; the store reports it as fatal and explains what to do. - ~~🟡 **`mv` is a guess.**~~ Resolved: the request sends no `mv`. That parameter selects the *flag* data model and the connection rejects any value but the flag default, while the generic agent-skill payload is served regardless of it. The `data_model_version` constructor argument is gone with it. - 🟡 **No payload signing** on this channel yet, so Beta is TLS-only. - 🟡 **The connection also carries the environment's flags.** Skipped and counted; a transport property, not fixable here. - 🟡 **`ld-relay` does not speak the FDv2 endpoints**, so relay-only deployments cannot receive skills in Beta. **Nothing here has touched a real LaunchDarkly environment**, because it cannot yet. 🤖 Generated with [Claude Code](https://claude.com/claude-code) <!-- CURSOR_SUMMARY --> --- > [!NOTE] > **Overview** > Adds **`FDv2SkillStore`**, a production `SkillStore` that pulls agent skills over LaunchDarkly’s SDK FDv2 **`/sdk/poll`** and **`/sdk/stream`** endpoints (stdlib HTTP, background delivery thread, stream-by-default). It implements **`SkillStore`** (`get_object`, listeners, etc.) on top of the existing protocol reader, plus **`StoreDiagnostics`**, **`wait_for_skills`**, capped backoff with **`Retry-After`**, and **`close`** that interrupts blocked socket reads so shutdown is prompt. > > **Public surface:** `FDv2SkillStore` and `StoreDiagnostics` are exported from the package; README documents production setup with `init_client` and `watch_skills`. Server-side SDK keys only; mobile/client credentials are rejected. Outages keep last-known-good content; accessors above the store are unchanged. > > **Delivery-loop fixes** bundled here: reset consecutive-failure counts on successful commits / up-to-date answers (so healthy stream recycling does not stop delivery), safe handling of non-finite **`Retry-After`**, and not treating intentional **`close`** interrupts as transport failures. Removed unused **`connect_timeout`**; **`read_timeout`** is the single knob with mode-specific defaults. > > **Tests:** in-process fake FDv2 server exercises poll/stream, basis/ETag/304, revocations, retries, timeouts, hashless payloads, and **`watch_skills`** over the transport. > > <sup>Reviewed by [Cursor Bugbot](https://cursor.com/bugbot) for commit 88c225e. Bugbot is set up for automated code reviews on this repo. Configure [here](https://www.cursor.com/dashboard/bugbot).</sup> <!-- /CURSOR_SUMMARY -->
…network (#82) Stacked on the `watch_skills` PR (`xie/skills-watch`). Second of three PRs split out of #69; the transport that puts a connection underneath this follows. The half of the delivery transport that has no I/O: identifying a skill object on the wire, translating it into the raw object shape the `SkillStore` interface defines, holding it by `(key, objectVersion)`, and applying a payload's events as one consistent commit. Splitting it out lets the three decisions that matter most be reviewed without a socket in the way. ## Three things worth reviewing closely **1. The skill's version is in the object's `key`; `version` is the payload's.** Each version of a skill is its own object on the wire, identified as `<key>:<version>` (`pdf-extraction:3`), and that is the only place the skill's version appears. The event's `version` is the payload's, and confusing the two fails *silently*: the object verifies, the hash matches, and the caller gets content under a version number that means nothing. The wire key is split in exactly one place (`_split_wire_key`), both the put and the delete translation go through it, and `TestVersionTranslation` asserts it in both directions. A key that will not split cleanly is *held* rather than dropped — version-less, or with the offending text as its version — so verification withholds it with `invalid_version` under a key the caller recognises; only a key with nothing before the delimiter is dropped. **2. Changes commit at `payload-transferred`, not per object.** A payload version is the unit of consistency. A half-applied full transfer would publish a state the server never described and would briefly empty the store, which, with pruning on, is the difference between a reconcile and deleting a customer's skill files. An interrupted transfer leaves last known good intact, and listeners fire once per commit. **3. A hashless object is held, not dropped.** Dropping it at the transport would report `absent`, indistinguishable from "no such skill", and would let a prune delete the last known-good copy on disk. Holding it means verification withholds it with `missing_content_hash`, which is diagnosable: an ERROR per `(key, version)`, deduped per reader rather than per process so two stores never quieten each other, a summary per wholly-hashless payload, and a `StoreDiagnostics.hashless_objects` counter. There is deliberately no fallback that synthesises a hash from the delivered content. ## Also here - **Skills are `kind == "skill"`; everything else is ignored, not rejected.** Object kinds on the SDK-facing channel are open strings and the agent-skill payload is classified `generic`, so a skill arrives under the kind its producer registered — the bare category name — with no `category` or `objectVersion` field ([streamer #4681](launchdarkly/streamer#4681), [gonfalon #70638](launchdarkly/gonfalon#70638)). An environment's assignment carries its flag payload alongside its agent-skill payload, so flag and segment objects arrive as a matter of course. Erroring on them would turn a normal payload into a permanent reconnect loop. - **`_SkillObjectSet`** holds several versions of one key, with lookup semantics identical to `InMemorySkillStore` down to the fall-through to a version-less entry. Its opaque snapshot keys are spelt `<key>:<version>`, the same as the wire, and a test pins that round trip. `TestInterfaceParity` asserts the two resolve identically. - **`_require_server_side_credential`** refuses a mobile key or client-side environment ID. Its tests arrive with the store constructor that calls it. Nothing here is exported yet; the store exports it. The module imports nothing from the feature but the version validator. ## Tests `test_skills_fdv2.py` drives `_ProtocolReader` directly: identification, version translation, full and change transfers, interruption, revocation, tombstones, mixed payloads, unknown kinds and events, error and goodbye, and the hashless dedupe across readers. The wire builders it introduces are shared with the transport PR's fake endpoint. 🤖 Generated with [Claude Code](https://claude.com/claude-code) <!-- CURSOR_SUMMARY --> --- > [!NOTE] > **Overview** > Adds **`skills_fdv2.py`**, a stdlib-only layer below `SkillStore` that parses LaunchDarkly FDv2 events without sockets. It maps wire `put-object`/`delete-object` into the raw store shape, keeps skills in **`_SkillObjectSet`**, and applies updates atomically in **`_ProtocolReader`** at **`payload-transferred`** (not per object). > > The critical wire rule is **`key` = `skillKey:objectVersion`** while the event’s **`version` is the payload revision** and is dropped—confusing them would silently serve the wrong pinned version. Non-`kind == "skill"` objects (flags, segments) are **ignored**, not errors. **Foreign payload** full transfers are declined once skills’ payload id is known, so a flag `xfer-full` cannot wipe held skills (and trigger prune). **Hashless** skills are retained for verification to withhold with `missing_content_hash`, with **`StoreDiagnostics`** and loud logging. **`_require_server_side_credential`** rejects mobile/client credentials (for the upcoming networked store). > > **`agents.md`** documents the transport contract; **`skills_core`** clarifies `SKILL_OBJECT_KIND` vs wire kind. **`test_skills_fdv2.py`** (~900 lines) exercises the reader, version translation, payload identity, and parity with `InMemorySkillStore`. Nothing is exported or wired from accessors yet—that’s the follow-on transport PR. > > <sup>Reviewed by [Cursor Bugbot](https://cursor.com/bugbot) for commit efc4ca7. Bugbot is set up for automated code reviews on this repo. Configure [here](https://www.cursor.com/dashboard/bugbot).</sup> <!-- /CURSOR_SUMMARY -->
…ls (#81) Stacked on #66 (`split/skills-review-closeout`). First of three PRs split out of #69; the FDv2 protocol layer and the transport follow on top of this one. `write_skills` is a one-shot reconcile, so a revocation takes effect at the next process restart. `watch_skills` runs that reconcile now and again whenever the configured store reports a change, so a revoked skill's `SKILL.md` leaves the disk within a debounce interval of the store learning about it, rather than at the next restart. ## What's here **`skills_watch.py`** — `watch_skills` / `SkillWatcher`. Wired to the `SkillStore` interface, not to any one transport: it needs a store that implements `add_listener` and nothing more. It refuses loudly when the store does not, because a watcher that silently never fires looks exactly like one whose skills never changed. The listener itself only sets an event; the reconcile runs on a single worker thread, debounced, so a burst of changes coalesces into one pass and a slow disk never stalls the store's delivery thread. A reconcile that raises is logged and the watcher continues. `on_unavailable="keep"` stays the default: an outage must not read as "everything was revoked". **`remove_listener(kind, fn)`** joins `add_listener` as the optional second half of change notification, on the `SkillStore` contract and on `InMemorySkillStore`. `SkillWatcher.close()` needs it to detach; without it a store held every watcher ever created for the rest of its life. The watcher probes for it and skips detaching when a store does not implement it, so a customer's own store keeps working. ## Tests `test_skills_watch.py` drives the watcher through `InMemorySkillStore`, whose `put` notifies synchronously, and through small store doubles: initial reconcile, coalescing, refusal of a store without `add_listener`, detaching on close, and a store without `remove_listener`. Three tests on `InMemorySkillStore.remove_listener` join `test_skills.py`. The end-to-end case, a `delete-object` arriving over a live connection and pruning a file, lands with the transport PR where the fake endpoint lives. 🤖 Generated with [Claude Code](https://claude.com/claude-code) <!-- CURSOR_SUMMARY --> --- > [!NOTE] > **Overview** > Adds **`watch_skills`** and **`SkillWatcher`** so agent skill files stay in sync with the configured skill store without waiting for a process restart. The API runs an initial `write_skills` reconcile, then listens for store delivery changes and re-reconciles on a **debounced background thread** (listener only wakes the worker; disk I/O never blocks the delivery thread). Revocations can prune `SKILL.md` within the debounce window. **`on_unavailable="keep"`** remains the default so transport outages are not treated as mass revocations. > > Extends the optional **`SkillStore`** change-notification contract with **`remove_listener(kind, fn)`**, implemented on **`InMemorySkillStore`**, so **`SkillWatcher.close()`** can detach; stores without it still work but keep listeners registered. **`watch_skills`** raises if no store is configured or the store lacks **`add_listener`**, and cleans up the listener if the initial reconcile fails. > > Public exports and README/agents docs are updated; new tests cover watcher behavior (coalescing, mid-startup revocations, close/detach) and **`remove_listener`** semantics. > > <sup>Reviewed by [Cursor Bugbot](https://cursor.com/bugbot) for commit 29ad3fe. Bugbot is set up for automated code reviews on this repo. Configure [here](https://www.cursor.com/dashboard/bugbot).</sup> <!-- /CURSOR_SUMMARY -->
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Cursor Bugbot has reviewed your changes using default effort and found 1 potential issue.
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| committed=True, | ||
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| basis=state if isinstance(state, str) and state else None, | ||
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Foreign transfer overwrites reconnect basis
Medium Severity
A declined foreign-payload transfer still returns committed=True with that transfer's state as basis. _apply then stores it as the reconnect cursor, so the next poll or stream follows the ignored payload rather than the skill one. Skill updates and revocations can stall even though the in-memory set was correctly left unchanged.
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Stacked on #58. Closes the four items left open in our response to the Agent Skills security design review.
Three documentation items and one test item. No behavior changes — the code halves of rows 9 and 2 were already done and are deliberately untouched; the only change to
safe_fs.pyis its module docstring.1. Privilege separation (row 9 docs half + counter-proposal for row 26)
The proposed mitigation for AZ-1, the review's most serious finding.
The README now documents reconcile-identity ≠ agent-identity as the recommended deployment, which is the whole reason the
0644/0755modes deny anything: the agent reads its instructions and cannot rewrite them, or the manifest. Write access to the manifest is the worse half — it is what tells the next reconcile which paths the SDK may delete — which is why_prunere-validates every entry from scratch rather than trusting it.The operator gets an explicit check to run, because the SDK cannot run it.
ReconcileReportdeliberately grows no writability field. Row 26 asked for one; we declined. The SDK knows only its own identity, which trivially has write access, having just written there. Any check it could make would answer a different question than the one asked and manufacture false confidence exactly where the review wants caution.agents.mdrecords that reasoning so the field is not added later by someone reading its absence as an oversight.2. Three hostile-manifest prune tests (row 12 remainder)
A well-formed manifest listing
/etc/passwd,../../../etc/passwd, and a path under a parent that has since become a symlink._prunealready refuses all three; these turn asserted into verified.Two things make them worth more than their line count:
/etc/passwdstill exists. The test process cannot delete that file anyway, so the obvious assertion would pass against an implementation with no path check at all — permissions would be doing the work. The spy proves the removal is never attempted.3. One sentence on
"*"(row 16 remainder)It materializes the whole project library, so every skill's
descriptionenters the agent's context — including skills no AI Config references and skills belonging to other teams.4. Windows platform bound (row 2 residual) — deferred, explicitly
Decision: defer, with the bound written down. Reparse-point checks (
GetFileAttributesW/FILE_FLAG_OPEN_REPARSE_POINT) are not implemented, and that is now recorded insafe_fs.py,agents.mdand the README rather than left implied.Rationale:
ubuntu-latest— so the checks would ship unverified. Both codebases already cite that absence as a reason not to addos.name/process.platformbranches.*at()family on any platform, so its racylstatfloor is universal rather than Windows-only. Hardening Python alone would break the cross-language parity the two SDKs are held to.Two consequences are recorded rather than left to be rediscovered: on Windows write permission on the managed root is the only boundary, which is what makes privilege separation the mitigation and not merely advice; and this retroactively lowers the priority of the row 25 reserved-device-name work, noted where that code lives. That code stays — it keeps a root written on Linux usable when read from Windows — but it is not evidence that Windows is hardened.
Parity
The Node half is launchdarkly/js-ai-sdk#48, case for case. No customer-visible surface moved: the
ld.skills.integrity_failureevent name, the eightreason_codetokens, the fiveSkillOutcomeReasontokens, and the log-record serialization are untouched.Verification
uv run pytest— 1484 passed, 11 skippeduv run ruff check ./ruff format --check .— cleanuv run mypy packages/*/src(the CI gate) — no issues in 43 source files🤖 Generated with Claude Code
Note
Overview
This PR extends Agent Skills with production delivery and live disk sync, plus security-review documentation and a small store API tweak.
New capabilities:
FDv2SkillStorepulls skill objects from LaunchDarkly over FDv2 (/sdk/polland/sdk/stream), translates wire keys (key:versionvs payloadversion), commits only atpayload-transferred, ignores non-skill objects, and exposesStoreDiagnostics/failed.watch_skillsruns an initialwrite_skillsthen debounced re-reconciles when the store notifies changes (for fast revocation on stream). Both are exported fromlaunchdarkly_ai_server;InMemorySkillStoreandFDv2SkillStoregainremove_listenerforSkillWatchercleanup. The no-storeRuntimeErrornow namesFDv2SkillStorebeforeInMemorySkillStore.Documentation (no new fs behavior in code beyond docstrings): README and
agents.mdadd FDv2/watch_skillsusage, warn that"*"materializes the whole library, document POSIX-only descriptor pinning vs Windows’ weaker boundary, and document privilege-separated reconcile vs agent identity (with a shell check)—explicitly not adding a managed-root writability field onReconcileReport.safe_fs.py’s module doc records the same Windows deferral.Tests:
remove_listenerbehavior and ordering of store names in the no-store error message.Reviewed by Cursor Bugbot for commit 09d7b60. Bugbot is set up for automated code reviews on this repo. Configure here.