* Studio: require signed capability tokens for /p preview links
The public /p preview routes added in #6486 run model load and chat
generation as the admin user with no authentication. The only gate is the
preview ref, a deterministic outputs-root path (run or run/checkpoint) that
is guessable rather than secret. On a network-reachable Studio (--secure
tunnel or -H 0.0.0.0), an unauthenticated caller who guesses a ref can
consume GPU and probe a private fine-tuned checkpoint.
Make the share link an unguessable, revocable capability:
- Sign the canonical ref with a dedicated server-side secret (HMAC-SHA256,
stored in app_secrets, independent of the JWT/login secret).
- Require a valid token on every /p chat, models, and page request before
resolving a checkpoint or loading a model; missing or invalid tokens get a
generic 404 so the surface never confirms a ref exists.
- Accept the token via ?k= (browser link and preview page) or
Authorization: Bearer (OpenAI-compatible clients).
- Rotate the secret to revoke every outstanding link
(POST /api/settings/preview-links/rotate).
- Clamp preview generation (max_tokens/max_completion_tokens <= 1024, n = 1)
and set Referrer-Policy: no-referrer on the page so the token is not
leaked via Referer.
Training history hands the authenticated owner the signed token, and the
copy-link button builds /p/{ref}?k={sig}.
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* Studio: honor a lower caller token limit in the preview clamp
Codex review: when only the legacy max_tokens was sent, the clamp left
max_completion_tokens at the 1024 default, and _effective_max_tokens prefers
max_completion_tokens, so a request like max_tokens=16 could still generate up
to 1024 tokens. Derive one effective limit (max_completion_tokens wins, else the
legacy max_tokens) and pin both fields to it so a caller's lower limit is kept.
* Studio: add preview kill switch, rate limit, and revoke-links UI
Follow-ups to the /p preview capability work:
- Public-sharing kill switch: a persisted setting (default on) gates the public
/p surface. When off, every preview request 404s even with a valid token, and
the owner UI stops offering share links. GET/PUT /api/settings/preview-sharing;
enforced in _verify_or_404.
- Per-IP rate limit on the preview chat route: a coarse in-process sliding-window
limiter (20 req/min/IP) returns 429 + Retry-After before the GPU lock is taken.
Client IP honors X-Forwarded-For only when UNSLOTH_STUDIO_TRUST_FORWARDED is
set, matching the login limiter's trust model.
- Settings UI: a "Preview sharing" section with the public-sharing toggle and a
"Revoke all preview links" button (confirm dialog) that rotates the secret.
Tests cover the kill switch (404 when off), the 429 path, the sliding window,
client-IP trust behavior, and the setting default.
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* Studio: fix preview-fields sharing arg and refresh sigs after revoke
Codex review:
- P1: get_training_run_detail and update_training_run called _preview_fields
with only output_dir after it gained a required sharing_on parameter, raising
a 500 TypeError once get_run succeeded. Pass get_preview_sharing_enabled() at
both sites; add a detail-endpoint regression test.
- P2: after rotating the preview secret from settings, the history grid still
held stale preview_sig values, so a freshly copied link would 404. Emit
emitTrainingRunsChanged() after a successful revoke so the grid refetches
freshly signed refs.
* Studio: harden preview sharing controls (Codex review)
- Fail closed: a read failure on the preview-sharing kill switch now returns
False instead of defaulting to enabled, so an unavailable settings DB can't
reopen the public surface. A missing key still defaults to enabled.
- Per-IP rate limit behind the managed Cloudflare tunnel: client_ip now honors
CF-Connecting-IP when the socket peer is loopback, so tunneled visitors are
keyed by their real IP instead of collapsing onto the local cloudflared peer.
- GET /p no longer mints key/share_url when sharing is disabled; it returns
sharing_enabled=false so clients don't distribute links that 404.
- Settings UI: toggling public sharing emits the training-runs-changed event so
the history grid shows/hides Copy preview link without a manual refresh.
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* Studio: harden preview rate limiter and IP keying (Opus review)
From a two-agent review of the PR:
- Rate limiter no longer evicts an active bucket when the table is full: a flood
of distinct keys could otherwise cycle out a throttled bucket and reset its
counter. Evict only aged-out buckets; if the table is full of live clients,
fail closed (deny the new key) instead.
- client_ip keys on the rightmost (proxy-appended) X-Forwarded-For hop when the
trust env is set; the leftmost is client-spoofable. Documented the
append/overwrite-proxy assumption.
- _verify_or_404 checks the capability token before the kill-switch DB read, so
unauthenticated /p spam can't be used as an unbounded settings-DB sink and the
response is identical regardless of the sharing on/off state.
Tests: nested run/checkpoint happy path + wrong-ref rejection, the eviction
fail-closed behavior, and route-level coverage for the rotate / preview-sharing
settings endpoints.
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Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
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