* Studio: make stop button actually stop generation
The UI stop button routes through assistant-ui's cancelRun, which aborts
the frontend fetch. Four issues combined to let llama-server keep decoding
long after the user clicked stop:
1. request.is_disconnected() does not fire reliably behind proxies
(e.g. Colab) that don't propagate fetch aborts.
2. llama-server defaults n_predict to n_ctx when max_tokens is not sent,
so a cancelled request keeps producing tokens up to 262144.
3. The httpx.Client pool keeps TCP keep-alive, so even a cleanly closed
stream reuses the same connection and llama-server's liveness poll
never sees a disconnect.
4. No explicit backend route to cancel - every cancel path relied on
is_disconnected.
Changes:
- Add POST /api/inference/cancel keyed by session_id/completion_id, with
a registry populated for the lifetime of each streaming response.
- Have the frontend (chat-adapter.ts) POST /inference/cancel on
AbortController abort, alongside the existing fetch teardown.
- Send max_tokens=4096 + t_max_predict_ms=120000 as defaults on every
outbound chat completion to llama-server; honoured by user overrides.
- Disable httpx keep-alive on the streaming client so connection close
reaches llama-server and its 1s liveness check fires.
No behaviour changes for non-streaming paths or for existing callers
that already pass max_tokens/session_id.
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* studio: harden stop-button cancel path and scope cancel route
- Require at least one identifier for /api/inference/cancel so a missing
thread id cannot silently cancel every in-flight generation.
- Scope /cancel to a dedicated studio_router so it is not exposed under
the /v1 OpenAI-compat prefix as a surprise endpoint.
- Store a set of cancel events per key in _CANCEL_REGISTRY so concurrent
requests on the same session_id do not overwrite each other, and
deduplicate in _cancel_by_keys so the cancelled count reflects unique
requests.
- Always send session_id with chat completions (not only when tools are
enabled) so non-tool GGUF streams register under it and are reachable
from /cancel.
- Register the non-GGUF stream_chunks path in the cancel registry too,
so transformers-based stop-button works behind proxies that swallow
fetch aborts.
- Only apply the 2-minute t_max_predict_ms wall-clock cap when the
caller did not pass max_tokens, so legitimate long generations on
slow CPU/macOS/Windows supported installs are not silently truncated.
- Remove the abort listener on normal stream completion so reused
AbortSignals cannot fire a spurious cancel POST after the fact.
* studio: close cancel-race and stale-cancel gaps in stop path
- Register the cancel tracker before returning StreamingResponse so a
stop POST that arrives during prefill / warmup / proxy buffering
finds an entry in _CANCEL_REGISTRY. Cleanup now runs via a Starlette
BackgroundTask instead of a finally inside the async generator body.
- Add a per-run cancel_id on the frontend (crypto.randomUUID) and in
ChatCompletionRequest so /api/inference/cancel matches one specific
generation. Removes the stale-cancel bug where pressing stop then
starting a new run in the same thread would cancel the retry.
- Apply t_max_predict_ms unconditionally in all three llama-server
payload builders (previously gated on max_tokens=None, which made it
dead code for UI callers that always send params.maxTokens). Raise
the default to 10 minutes so slow CPU / macOS / Windows installs are
not cut off mid-generation.
- Make _cancel_by_keys refuse empty input (return 0) so a future
internal caller can not accidentally mass-cancel every in-flight
request.
- Accept cancel_id (primary), session_id, and completion_id on the
/api/inference/cancel route. Unify the three streaming sites on the
same _cancel_keys / _tracker variable names.
- Annotate _CANCEL_REGISTRY as dict[str, set[threading.Event]].
* Add review tests for PR #5069
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* studio: harden stop-button cancel semantics and wall-clock cap
- Make /inference/cancel match cancel_id EXCLUSIVELY when supplied.
Previously the handler iterated ('cancel_id','session_id','completion_id')
and unioned matches, so a stale cancel POST carrying {cancel_id:old,
session_id:thr} would still cancel a later run on the same thread via
the shared session_id. cancel_id is now a per-run exclusive key;
session_id / completion_id are only used as fallbacks when cancel_id
is absent.
- Close the early-cancel race. If /inference/cancel lands before the
streaming handler reaches _TrackedCancel.__enter__() (stop clicked
during prefill / warmup / proxy buffering), the cancel was silently
dropped. Stash unmatched cancel_ids in _PENDING_CANCELS with a 30 s
TTL; _TrackedCancel.__enter__() now replays any matching pending
cancel by set()-ing the event immediately after registration.
- Make t_max_predict_ms = _DEFAULT_T_MAX_PREDICT_MS conditional on
max_tokens is None at all three llama-server payload sites. The cap
is a safety net for callers who leave max_tokens unset (otherwise
llama-server defaults n_predict to n_ctx, up to 262144). Callers who
set an explicit max_tokens are already self-limiting and must not be
silently truncated at 10 minutes on slow CPU / macOS / Windows
legitimate long generations.
- Guard each StreamingResponse return with try/except BaseException so
_tracker.__exit__ runs even if StreamingResponse construction or any
preceding statement raises between _tracker.__enter__() and the
BackgroundTask attachment. Prevents a registry leak on that narrow
window.
* studio: close TOCTOU race and restore wall-clock backstop on UI path
- Close TOCTOU race in the pending-cancel mechanism. The previous fix
split cancel_inference's (cancel_by_keys + remember_pending_cancel)
and _TrackedCancel.__enter__'s (register + consume_pending) into
four separate lock acquisitions. Under contention a cancel POST
could acquire-then-release the lock, find the registry empty, and
stash ONLY AFTER __enter__ had already registered and consumed an
empty pending map -- silently dropping the cancel. Both call sites
now do their work inside a single _CANCEL_LOCK critical section, via
the new atomic helper _cancel_by_cancel_id_or_stash() and an
inlined consume-pending step in __enter__. Reproduced the race under
forced interleaving pre-fix; 0/2000 drops post-fix under parallel
stress.
- Apply t_max_predict_ms UNCONDITIONALLY at all three llama-server
payload sites. The previous iteration gated the cap on
`max_tokens is None`, which turned out to be dead code on the
primary Studio UI path: chat-adapter.ts sets
maxTokens=loadResp.context_length after every model load, so every
chat request carries an explicit max_tokens and the wall-clock
safety net never fired. The cap's original purpose is to bound
stuck decodes regardless of the token budget; it must always apply.
- Raise _DEFAULT_T_MAX_PREDICT_MS from 10 minutes to 1 hour. 10
minutes was too aggressive for legitimate slow-CPU chat responses
(a 4096-token reply at 2 tok/s takes ~34 min); 1 hour accommodates
that and still catches genuine zombie decodes.
- Prune _PENDING_CANCELS inside _cancel_by_keys as well, so stashed
entries expire proportionally to overall cancel traffic rather than
only to cancel_id-specific POSTs.
* studio: trim verbose comments and docstrings in cancel path
* studio/llama_cpp: drop upstream PR hashes from benchmark comment
* Add review tests for Studio stop button
* Consolidate review tests for Studio stop button
* Align cancel-route test with exclusive cancel_id semantics
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* studio: move cancel cleanup to generator finally; drop dead helper
- Move _tracker.__exit__ from Starlette BackgroundTask into each
streaming generator's finally block. Starlette skips the background
callback when stream_response raises (OSError / ClientDisconnect),
which leaked _CANCEL_REGISTRY entries on abrupt disconnect.
- Check cancel_event.is_set() at the top of each GGUF while loop so a
pending-replay cancel falls through to final_chunk + [DONE] instead
of propagating GeneratorExit out of _stream_with_retry.
- Remove unused _remember_pending_cancel; _cancel_by_cancel_id_or_stash
superseded it.
* Add review tests for Studio stop-button
* studio: wire audio-input stream into cancel registry
- Register cancel_event with _TrackedCancel on the audio-input streaming
path so POST /api/inference/cancel can stop whisper / audio-input GGUF
runs. Previously the registry stayed empty on this branch, so the stop
button returned {"cancelled":0} and the decode ran to completion.
- Apply the same finally-based cleanup and pre-iteration cancel-event
check used on the other three streaming paths.
- Update the _CANCEL_REGISTRY block comment to list cancel_id as the
primary key (was stale "session_id preferred").
* Consolidate review tests for Studio stop-button cancel flow
- Merge the 6 behavioral tests from test_stream_cleanup_on_disconnect.py
(finally cleanup on normal/exception/aclose, pre-set cancel_event
pattern, and its regressions) into test_stream_cancel_registration_timing.py,
which is the PR's existing file covering the same area.
- Extend structural invariants to include audio_input_stream alongside the
three GGUF / Unsloth streaming generators: no _tracker.__enter__ inside
the async gen body, cleanup via try/finally, no background= on
StreamingResponse.
- Delete test_stream_cleanup_on_disconnect.py (now empty).
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* studio: make cancel-via-POST interrupt Unsloth and audio-input streams
Close two remaining gaps in the stop-button cancellation wiring:
- stream_chunks (Unsloth path): add a top-of-loop cancel_event check and
call backend.reset_generation_state() so cancel POSTs flush GPU state
and close the SSE cleanly instead of relying on request.is_disconnected
(which does not fire through proxies like Colab's).
- audio_input_stream: run the synchronous audio_input_generate() via
asyncio.to_thread so blocking whisper chunks do not freeze the event
loop, matching the pattern already used by the GGUF streaming paths.
* Add review tests for Studio stop-button cancel flow
* Consolidate review tests for Studio stop-button cancel flow
- Delete standalone test_cancel_registry.py at repo root: tests duplicated
test_cancel_atomicity.py / test_cancel_id_wiring.py and re-implemented
registry primitives inline (scaffolding).
- Extend tests/studio/test_stream_cancel_registration_timing.py with
regression guards for the iter-1 cancel-loop fixes:
structural: each streaming generator checks cancel_event in its loop;
audio_input_stream offloads next() via asyncio.to_thread;
stream_chunks cancel branch calls reset_generation_state().
runtime: Unsloth loop breaks on external cancel and resets state;
audio loop stays responsive under blocking next();
both loops emit zero tokens on pre-set cancel (replay path).
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* studio: extend stop-path to passthrough streams; tighten wall-clock cap
- Lower _DEFAULT_T_MAX_PREDICT_MS from 1 hour to 10 minutes so the
wall-clock backstop actually bounds runaway decodes when cancel
signaling fails.
- Wire _TrackedCancel and cancel_event.is_set() into
_openai_passthrough_stream and _anthropic_passthrough_stream and
disable httpx keepalive so stop requests from /v1 and /v1/messages
tool-calling clients reach llama-server.
- Apply t_max_predict_ms to the tool-passthrough request body so the
backstop covers passthrough paths as well.
- Symmetric pre-registration stash for session_id/completion_id
cancels (_cancel_by_keys_or_stash) so early cancels by those keys
replay on later registration like cancel_id.
- Drop dead except BaseException guards around StreamingResponse()
at four streaming sites; cleanup lives in the generator's finally.
* studio: harden cancel registry against ghost-cancel and leak paths
- Revert the session_id/completion_id stash in the fallback cancel
helper. session_id is thread-scoped and reused across runs, so
stashing it on an unmatched POST would fire cancel_event for the
user's next unrelated request via _TrackedCancel.__enter__.
cancel_id remains the only per-run unique key that gets stashed.
- Default max_tokens to _DEFAULT_MAX_TOKENS in the tool-passthrough
body. Mirror the direct GGUF path so OpenAI/Anthropic passthrough
callers who omit max_tokens get the same zombie-decode cap instead
of relying on the wall-clock backstop alone.
- Wrap _openai_passthrough_stream setup with an outer try/except
BaseException. The inner except httpx.RequestError does not catch
asyncio.CancelledError at await client.send, which would otherwise
leave _tracker registered in _CANCEL_REGISTRY indefinitely.
- Frontend stop POST uses plain fetch + manual Authorization header
instead of authFetch. A 401 on the cancel POST no longer refreshes
tokens or redirects the user to the login page mid-stop.
* Add review tests for Studio stop-button cancel flow
* studio: trim comments on stop-button review changes
Collapse multi-paragraph rationale blocks on the cancel registry,
_openai_passthrough_stream, and the frontend onAbortCancel handler
into one-line explanations of why the non-obvious behaviour exists.
Drop authFetch import that became unused when the cancel POST
switched to plain fetch.
* Consolidate review tests for Studio stop-button cancel flow
Move review-added tests out of test_cancel_dispatch_edges.py into the
existing PR test files that already cover the same areas:
- backend registry fan-out / exclusivity / idempotency / falsy-keys
edge cases moved into tests/studio/test_cancel_atomicity.py
- frontend plain-fetch (not authFetch) + manual Authorization header
moved into tests/studio/test_cancel_id_wiring.py
Delete the now-empty test_cancel_dispatch_edges.py.
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* Studio: stop default-capping responses at 4096 tokens (follow-up to #5069) (#5174)
* Studio: stop default-capping responses at 4096 tokens
Follow-up to #5069. The 4096 default introduced for runaway-decode
defense silently truncates any caller that omits max_tokens. The
Studio chat UI sets params.maxTokens = loadResp.context_length after
a GGUF load, so it's fine, but every other consumer is not:
- OpenAI-API direct callers (/v1/chat/completions, /v1/responses,
/v1/messages, /v1/completions) where the OpenAI default is
effectively unlimited per response. langchain, llama-index, raw
curl, and the openai SDK all rely on that.
- Reasoning models. Qwen3 / gpt-oss reasoning traces routinely exceed
4096 tokens before the model emits a single visible content token.
The user sees the trace cut off mid-thought.
- Long-form generation ("write a chapter", "produce a full SVG").
Reproduced on this branch: gemma-4-E2B-it-GGUF Q8_0, prompt asking
for a 10000-word story, no max_tokens in the request:
finish_reason: stop (misleading -- should be 'length')
content_chars: 19772
content_tail: ...'a comforting, yet immense, pressure.\n\n*"'
Body ended mid-sentence on a stray opening quote, right at the 4096
token mark.
After this patch the same request returns 38357 chars ending with
'...held in a perfect, dynamic equilibrium.' -- a natural stop, not
a truncation.
Implementation: rename the constant to _DEFAULT_MAX_TOKENS_FLOOR and
set it to 32768. Each call site now uses the model's effective
context length when known, falling back to the floor:
default_cap = self._effective_context_length or _DEFAULT_MAX_TOKENS_FLOOR
The 10-minute t_max_predict_ms wall-clock backstop from #5069 is
preserved as the second line of defense.
Plumbed _build_passthrough_payload + _build_openai_passthrough_body
through the routes layer so the Anthropic and OpenAI passthrough
paths also respect the model's context length.
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---------
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
* Studio: cancel passthrough streams during llama-server prefill + route through apiUrl for Tauri
Three reviewer-flagged correctness gaps in the stop-button mechanism.
1) `_openai_passthrough_stream` could not honor cancel during prefill.
The cancel check ran inside the `async for raw_line in lines_iter`
body, so a cancel POST that arrived before llama-server emitted the
first SSE line was unobservable until prefill completed. With a long
prompt under proxy/Colab conditions -- the exact target scenario for
this PR -- that left the model decoding for a long time after the
user clicked Stop. Add an asyncio watcher task that closes `resp` as
soon as `cancel_event` is set, raising in `aiter_lines` so the
generator can exit. The watcher polls a threading.Event because the
cancel registry is keyed by threading.Event for the synchronous
/cancel handler.
2) `_anthropic_passthrough_stream` had the same blocking-prefill pattern.
Same fix.
3) The frontend's stop-button cancel POST used a bare relative
`fetch("/api/inference/cancel", ...)`, which targets the webview
origin in Tauri production builds (where the backend is at
`http://127.0.0.1:8888`). Route through the existing `apiUrl()`
helper from `lib/api-base.ts` to match every other Studio call.
Browser/dev builds get the empty base, so behavior is unchanged
there.
Verified via temp/pr_simulation/sim_5069_prefill_cancel.py: cancel
during prefill terminates within ~250ms on both passthrough paths
(was 145s+ on the Anthropic path before this change), and the standard
non-passthrough chat path still cancels with no regression.
* Studio: log cancel-body parse errors instead of silently swallowing
Reviewer-flagged defensive logging gap. The bare `except Exception: pass`
in `cancel_inference` would mask malformed payloads that hint at a buggy
client or a transport issue. Log at debug so future investigation isn't
left guessing whether `body={}` came from a missing body or a parse
failure. Behavior is unchanged: an unparseable body still falls through
to the empty-dict path and the cancel call returns `{"cancelled": 0}`.
* Studio: Anthropic passthrough cancel parity with OpenAI passthrough
Two reviewer-flagged consistency gaps in the cancel surface for
/v1/messages.
1) Anthropic passthrough did not register cancel_id, so a per-run cancel
POST (the cleanest Studio-style cancel path) silently missed when
the route hit `_anthropic_passthrough_stream`. The OpenAI passthrough
has registered (cancel_id, session_id, completion_id) since this PR
was first opened; mirror that here. Also add `cancel_id` to
`AnthropicMessagesRequest` so the route handler can plumb it through.
2) The cancel handler's fallback key list checked only completion_id
and session_id, never message_id. Anthropic clients that send their
native `id` (returned in the SSE message_start event) for cancel had
no way to hit the registry. Add message_id to the fallback list.
Verified via temp/pr_simulation/sim_5069_prefill_cancel.py: P2 now
cancels by cancel_id in 137ms (was hanging pre-fix), and the new P2b
case cancels by message_id in 77ms. P1 (OpenAI) and P3 (standard chat)
still pass with no regression.
---------
Co-authored-by: danielhanchen <michaelhan2050@gmail.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Roland Tannous <115670425+rolandtannous@users.noreply.github.com>
Co-authored-by: Lee Jackson <130007945+Imagineer99@users.noreply.github.com>
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