<!-- This is an auto-generated description by cubic. -->
## Summary by cubic
Show a clear hint when `browser-use` runs piped code that references an
unknown helper, and unify the CLI 3.0 guidance across errors and
migration hints. Tighten detection so only `NameError`s raised by user
code are wrapped.
- **New Features**
- On `NameError` from exec’d stdin, print the traceback, then a friendly
message to stderr (example, core helpers, install steps, docs link,
`browser-use --doctor`) and exit with code 2. Shared `_CLI3_GUIDE` is
used in both the unknown-helper hint and legacy migration message.
- **Bug Fixes**
- Only treat `NameError` from the final frame of piped code (`<string>`)
as an unknown helper; internal/helper `NameError`s propagate.
<sup>Written for commit 36a8525c13.
Summary will update on new commits.</sup>
<a
href="https://cubic.dev/pr/browser-use/browser-use/pull/5171?utm_source=github"
target="_blank" rel="noopener noreferrer"
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<!-- End of auto-generated description by cubic. -->
The `browser-use skill sync` check compares the committed SKILL.md
copies against browser-harness main, which recently gained the
cloud-browser-suggestion section. The committed copies were stale, so
the check fails on every PR (it also failed on #5169, unrelated to that
PR's changes).
This re-runs `scripts/sync_browser_harness_skill.py` to bring both
copies current. `--check` passes locally.
<!-- This is an auto-generated description by cubic. -->
---
## Summary by cubic
Syncs the `browser-use` SKILL.md copies with browser-harness main by
adding the cloud-browser guidance section, fixing the `browser-use skill
sync` check that was failing on every PR. Re-ran
`scripts/sync_browser_harness_skill.py`; `--check` passes locally.
<sup>Written for commit 9fb49e03ee.
Summary will update on new commits.</sup>
<a
href="https://cubic.dev/pr/browser-use/browser-use/pull/5170?utm_source=github"
target="_blank" rel="noopener noreferrer"
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<!-- End of auto-generated description by cubic. -->
<!-- This is an auto-generated description by cubic. -->
## Summary by cubic
Adds a quickstart and better stdin handling to the `browser-use` CLI
when run without args, guiding new users and preventing empty runs.
- **New Features**
- Show a quickstart message and exit 0 when `browser-use` is invoked
with no args in a TTY.
- Run piped Python from stdin; if stdin is empty, print a hint with
usage and exit 1.
<sup>Written for commit 755083ebe5.
Summary will update on new commits.</sup>
<a
href="https://cubic.dev/pr/browser-use/browser-use/pull/5169?utm_source=github"
target="_blank" rel="noopener noreferrer"
data-no-image-dialog="true"><picture><source
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<!-- This is an auto-generated description by cubic. -->
## Summary by cubic
Removed in-repo telemetry and delegated CLI event reporting to
`browser_harness` for unified, simpler telemetry. No user-facing
behavior changes; events report via Harness when available.
- **Refactors**
- Removed PostHog sender and `CLITelemetryEvent`; cleaned up exports and
dead code in `telemetry/*`.
- Added `_capture_via_harness` that calls
`browser_harness.telemetry.capture_cli_event` if present, and
`_set_harness_client_env` to set `BH_CLIENT`/`BH_CLIENT_VERSION`.
- Added `_delegated_to_harness` to prevent double-reporting; only
capture when not delegated.
- Simplified CLI telemetry context by dropping agent/model detection,
task parsing, and mode tracking; kept only command name.
- **Migration**
- If you imported `browser_use.telemetry.CLITelemetryEvent` or
`capture_detached`, switch to
`browser_harness.telemetry.capture_cli_event`.
<sup>Written for commit d1af39626e.
Summary will update on new commits.</sup>
<a
href="https://cubic.dev/pr/browser-use/browser-use/pull/5165?utm_source=github"
target="_blank" rel="noopener noreferrer"
data-no-image-dialog="true"><picture><source
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<!-- This is an auto-generated description by cubic. -->
## Summary by cubic
Renamed all non-URL mentions of "browser-harness" to "browser-use" in
generated skill docs to prevent broken links and simplify the logic.
- **Refactors**
- Replaced multiple targeted string replacements with a single regex
that skips URL path segments (uses `re.sub(r'(?<!/)browser-harness',
'browser-use', body)`).
<sup>Written for commit 53b1316076.
Summary will update on new commits.</sup>
<a
href="https://cubic.dev/pr/browser-use/browser-use/pull/5161?utm_source=github"
target="_blank" rel="noopener noreferrer"
data-no-image-dialog="true"><picture><source
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<!-- End of auto-generated description by cubic. -->
<!-- This is an auto-generated description by cubic. -->
## Summary by cubic
Fixes CLI slowdowns by sending telemetry in a detached helper with a 5s
network timeout, and adds better error context via the stderr tail. Also
improves agent detection and sends a truncated task for easier
debugging.
- **Bug Fixes**
- Telemetry is sent via a detached helper to avoid blocking the CLI;
respects `ANONYMIZED_TELEMETRY` and uses a 5s send timeout.
- Error events include the last 500 chars of stderr as context when
available.
- **New Features**
- Broader agent client detection via env markers (e.g., Cursor, Copilot,
Claude Code, Gemini CLI, OpenClaw, Hermes, CodeX, Amp).
- Sends a truncated task (up to 20k chars) instead of fully redacting;
device ID is unified, persisted, and falls back to a machine
fingerprint.
<sup>Written for commit 2d01ea316f.
Summary will update on new commits.</sup>
<a
href="https://cubic.dev/pr/browser-use/browser-use/pull/5150?utm_source=github"
target="_blank" rel="noopener noreferrer"
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<!-- End of auto-generated description by cubic. -->
## Problem
`is_element_visible_according_to_all_parents` mutated
`node.snapshot_node.bounds` **in place** while walking the frame chain
(`dom/service.py:295-296, 333-334`):
1. Every checked node's bounds were permanently shifted by frame offsets
and scroll, corrupting coordinates shared with `absolute_position` math,
paint-order filtering, and iframe hidden-element counting. The check
wasn't even idempotent — calling it twice on the same node could return
different results.
2. A frame node appears in **its own** frame chain
(`_construct_enhanced_node` appends it before computing its visibility),
so an iframe's bounds got offset by themselves — coordinates doubled. An
iframe at y=1200 on a 900px viewport (threshold 1000) became y=2400 →
classified invisible → `should_process_iframe=False` → its entire
content subtree silently dropped from extraction. A likely contributor
to "elements missing from the DOM" reports and one of the reasons
cross-origin iframe support has been flaky.
## Fix
Work on a copy of the bounds; skip `frame is node` in the chain walk. No
behavioral change for correctly-classified elements.
## Verification
New unit tests (no browser needed) that fail on the previous code:
- bounds object unchanged after a visibility check
- the check is idempotent
- an iframe checked against a frame chain containing itself is not
double-transformed (y=1200 stays visible)
Plus existing DOM serializer browser tests passing; pyright and ruff
clean.
Part of a series of small fixes from an internal review (#5133, #5146,
#5147, #5148).
<!-- This is an auto-generated description by cubic. -->
---
## Summary by cubic
Fixes a visibility bug that mutated shared bounds and double-offset
iframes. We now copy bounds and skip self in the frame chain, restoring
correct visibility and preventing dropped iframe content.
- **Bug Fixes**
- Copy `snapshot_node.bounds` before transforms to avoid in-place
mutations.
- Skip `frame is node` when walking the frame chain to prevent double
transforms.
- Add tests for non-mutation and iframe visibility; strengthen the
idempotency test to catch drift at threshold.
<sup>Written for commit 94ea8f60c8.
Summary will update on new commits.</sup>
<a
href="https://cubic.dev/pr/browser-use/browser-use/pull/5151?utm_source=github"
target="_blank" rel="noopener noreferrer"
data-no-image-dialog="true"><picture><source
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<!-- End of auto-generated description by cubic. -->
is_element_visible_according_to_all_parents mutated snapshot_node.bounds in
place while walking the frame chain, permanently shifting every checked
node's coordinates by frame offsets and scroll — corrupting values shared
with absolute_position math, paint-order filtering, and any later visibility
check (the function was not even idempotent).
Worse, a frame node appears in its own frame chain (_construct_enhanced_node
appends it before computing visibility), so an iframe's bounds were offset
by themselves — coordinates doubled — wrongly classifying iframes past
half the viewport threshold as invisible and silently dropping their entire
content subtree from extraction.
Work on a copy of the bounds and skip self in the frame chain.
## Problem
When structured output hits the completion-token cap, the JSON arrives
cut mid-string. Nothing checked `finish_reason`/`stop_reason` anywhere
(`grep stop_reason browser_use/agent/service.py` → no hits), so users
saw either:
- an opaque `Unterminated string starting at...` / pydantic validation
error, or
- **worse**: a valid-but-chopped answer, if truncation landed between
JSON fields — silent partial answers.
With `ChatOpenAI`'s default `max_completion_tokens=4096`, this regularly
hits long `done(text=...)` and `extract` outputs. The real cause was
never surfaced.
## Fix
Each provider checks its truncation signal before parsing structured
output and raises a clear error naming the cause and the knob:
- **OpenAI** (`finish_reason == 'length'`): raise
`ModelProviderError('Model output was truncated at
max_completion_tokens=N; ... increase max_completion_tokens or request
shorter output')`
- **Anthropic** (`stop_reason == 'max_tokens'`): same, for the tool_use
input path; plus an `except ModelProviderError: raise` guard so the new
error isn't re-wrapped by the generic catch-all into a status-502 blob
- **Google** (`MAX_TOKENS` finish reason): shared
`_raise_if_output_truncated()` helper applied to both the structured
path and the fallback text path
Status code **400** is deliberate: it's not in any provider's retryable
set (Google retries 429/5xx), and retrying an identical request would
truncate identically.
## Verification
- Regression test drives the **real OpenAI SDK** against a local
httpserver returning `finish_reason='length'` with JSON cut mid-string —
asserts the error names the truncation and the parameter, not a parse
failure (fails on previous code with the misleading validation error). A
companion test confirms normal `finish_reason='stop'` responses still
parse.
- 9 LLM tests passing; pyright and ruff clean.
Anthropic/Google paths are verified by type-checker and code-trace;
their SDK transports don't point at a local httpserver as easily —
follow-up welcome if there's an established fake for them.
Part of a series of small fixes from an internal review (#5133, #5146,
#5147).
<!-- This is an auto-generated description by cubic. -->
---
## Summary by cubic
Detect and surface LLM output truncation instead of misleading JSON
parse errors, and allow switching to a fallback LLM when truncation
occurs. Also handles reasoning models that return `content=null` with a
length-based finish reason.
- **Bug Fixes**
- OpenAI: If `finish_reason == 'length'`, raise
`ModelOutputTruncatedError` (400) before the missing-content guard;
reference `max_completion_tokens` or say "the model's output token
limit" when unset.
- Anthropic: If `stop_reason == 'max_tokens'`, raise
`ModelOutputTruncatedError`; add `except ModelProviderError: raise` so
the clear error isn’t re-wrapped.
- Google: Detect `MAX_TOKENS` in both structured and fallback paths via
`_raise_if_output_truncated`; raise (400) referencing
`max_output_tokens` or the generic phrase when unset.
- Agent: Introduced `ModelOutputTruncatedError` (400). Provider retry
loops skip it; the agent treats it as fallback-switchable so a
higher-cap model can succeed.
- Tests: Cover truncation vs normal parse, unset-cap message,
`content=None` case, and that truncation triggers a fallback LLM switch.
- **Refactors**
- Trimmed comments to essentials.
<sup>Written for commit 248f98f208.
Summary will update on new commits.</sup>
<a
href="https://cubic.dev/pr/browser-use/browser-use/pull/5148?utm_source=github"
target="_blank" rel="noopener noreferrer"
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<!-- This is an auto-generated description by cubic. -->
## Summary by cubic
Adds a legacy command shim to the `browser-use` CLI that detects pre-3.0
subcommands/flags and prints a short migration guide with examples. It
exits with code 2 and tags the run as `legacy:<cmd>` instead of running
the harness.
- **New Features**
- Detects common pre-3.0 commands and flags and maps them to clear
hints.
- Prints a structured migration message to stderr with stdin piping
examples, core helpers, and doc links.
- Exits with status 2 to signal misuse; avoids starting the browser
harness.
- Updates command context/dispatch to label events as `legacy:<cmd>` for
easier tracking.
<sup>Written for commit b65642f810.
Summary will update on new commits.</sup>
<a
href="https://cubic.dev/pr/browser-use/browser-use/pull/5149?utm_source=github"
target="_blank" rel="noopener noreferrer"
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OpenAI reasoning models can spend the entire max_completion_tokens budget on
hidden reasoning, returning finish_reason='length' with content=null. The
truncation check ran after the missing-content guard, so that case raised
the generic 'Failed to parse structured output' (500) instead of
ModelOutputTruncatedError — no truncation signal, no fallback switch. Check
finish_reason first; it does not depend on content.
The 400 status chosen for truncation errors (deliberately outside provider
retry lists — an identical retry truncates identically) also fell outside
Agent._try_switch_to_fallback_llm's allowlist, so a configured fallback_llm
could no longer rescue a truncated run. Before this PR the downstream parse
failure was wrapped as a 502 ModelProviderError, which did allow the switch.
Introduce ModelOutputTruncatedError(ModelProviderError, status 400): the
three providers raise it, provider retry loops still skip it, and the
agent's fallback check treats it as switchable explicitly — a fallback with
a different output cap can succeed where the primary truncated.
max_completion_tokens (OpenAI) and max_output_tokens (Google) are optional;
when set to None the truncation message printed 'truncated at
max_output_tokens=None'. Fall back to "the model's output token limit" —
a MAX_TOKENS/length finish reason means some server-side cap fired even
with no client-side cap configured. Anthropic's max_tokens is non-optional
and unaffected.
Gregor Žunič
