_maybe_follow_capture() issued a follow-up screenshot unconditionally
when capture_after=True, even when res.ok=False. The model then received
a normal-looking screenshot alongside an error message, and in practice
it often ignored ok=False and proceeded as if the action had succeeded.
Fix: return _text_response(res) early when res.ok is False so the model
receives only the error and can decide how to recover.
Tests added:
- test_capture_after_skipped_when_action_failed: patches click to return
ok=False and asserts no capture call is issued.
- test_capture_after_fires_when_action_succeeds: ensures the happy path
still triggers the follow-up capture.
_dispatch() routes action="set_value" to backend.set_value(), but:
- ComputerUseBackend did not declare set_value as @abstractmethod, so
subclasses could silently omit it without a TypeError at class load time.
- _NoopBackend (the test/CI stub) had no set_value method at all, causing
AttributeError in any test that exercises the set_value action path.
Fix:
- Add set_value as @abstractmethod to ComputerUseBackend in backend.py.
- Add a recording stub in _NoopBackend in tool.py.
- Add two TestDispatch cases: one verifying the call reaches the backend,
one verifying the missing-value guard returns a clean error.
The cherry-pick of #22891 (max_elements cap) reshuffled _capture_response
so summary was assigned inside both the multimodal and AX branches,
but #30126's aux-vision routing call (_route_capture_through_aux_vision)
fires BEFORE either branch and references the not-yet-bound name.
Compute summary once up-front, keep the AX-branch rebuild for the
truncation note.
Four findings from Copilot's review on PR #22891, all in the AX
elements-array cap added by 22fa1ed:
1. The truncation note ("response truncated to N of M elements") was
appended unconditionally — including in the som/vision multimodal
path, whose response carries a screenshot rather than an `elements`
array. The note described a payload field that wasn't present.
Moved the note into the AX-text branch where the array actually
appears.
2. `_format_elements(cap.elements)` ran on the full untrimmed list with
its own `max_lines=40` cap, so a caller passing `max_elements=10`
would see summary lines referencing `#11..#40` even though the JSON
`elements` array only held #1..#10. Format on `visible_elements`
instead so the summary indices always exist in the response.
3. `_coerce_max_elements` enforced a lower bound but no upper bound,
so `max_elements=10_000_000` silently disabled the safeguard and
reintroduced the original context-blow-up. Added a hard cap
(`_MAX_ALLOWED_MAX_ELEMENTS = 1000`) that clamps oversized values.
4. The schema string said "Default 100" but the property carried no
`default` field, and claimed `max_elements` had no effect on som/
vision while the image-missing fallback path can still return an
elements array. Added `"default": 100`, `"maximum": 1000`, and
clarified the fallback-path wording.
Each finding gets a regression test:
- test_capture_ax_clamps_oversized_max_elements_to_hard_cap
- test_capture_ax_summary_indices_match_returned_elements
- test_capture_multimodal_summary_omits_truncation_note
- test_schema_max_elements_documents_default_and_upper_bound
Verified with `pytest tests/tools/test_computer_use.py` (53 passed,
including the 5 new cases). Confirmed each new test fails on the
pre-fix code path before applying the production change.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
`computer_use(action='capture', mode='ax')` returned the full AX element
list verbatim in the JSON response. Dense Electron / Obsidian / JetBrains
UIs publish 500+ AX nodes (one reproduction in #22865 returned 597
elements against Obsidian), so a single capture could consume enough
context to trigger compression failures or render the session unusable.
The human-readable `_format_elements` summary is already capped at 40
lines, so the truncation gap was invisible to anyone reading the summary
output.
Add a `max_elements` argument to the tool schema, default 100, that
trims the AX `elements` array. When the cap fires, the response surfaces
`total_elements` and `truncated_elements` and appends a "raise
max_elements or pass app= to narrow" hint to the summary so the model
knows the JSON view is partial and can re-issue with a tighter scope.
Validation is centralized in `_coerce_max_elements`: missing /
non-integer / sub-1 inputs fall back to the default cap, so the
protection can never be silently disabled by a malformed tool-call
argument. The cap only affects AX-mode JSON; `mode='som'` and
`mode='vision'` keep returning a screenshot + image-aware summary
unchanged.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
When the active main model has no vision capability — or when the user
explicitly configured auxiliary.vision in config.yaml — sending the
captured screenshot back to the main model in a multimodal tool-result
envelope is the wrong move: it trips HTTP 404 / 400 at the provider
boundary (e.g. 'No endpoints found that support image input') and the
agent loop reports a hard tool failure for what should have been a
simple capture.
The reporter on #24015 hit this with:
model:
default: tencent/hy3-preview # no vision support
provider: openrouter
auxiliary:
vision:
provider: openrouter
model: google/gemini-2.5-flash # explicitly configured
…and observed:
computer_use(action='capture', mode='som')
→ ⚠️ API call failed (attempt1/3): NotFoundError [HTTP 404]
🔌 Provider: openrouter Model: tencent/hy3-preview
📝 Error: HTTP 404: No endpoints found that support image input
Fix: in tools/computer_use/tool.py::_capture_response, after a
screenshot is captured (modes 'som' / 'vision'), consult the routing
helper introduced earlier in this branch. When it says 'route to aux',
materialise the PNG to $HERMES_HOME/cache/vision/, run vision_analyze
on it (which honours auxiliary.vision via the standard async_call_llm
task='vision' router), and return a text-only JSON tool result that
embeds the analysis alongside the existing AX/SOM index. The main
model never sees the pixels — it sees an actionable text description
plus the same set-of-mark element index it normally uses.
The two new helpers (_should_route_through_aux_vision,
_route_capture_through_aux_vision) keep the policy and the IO
separated so each can be tested in isolation. Both fail open: if the
config import fails, if the aux call raises, or if the analysis is
empty, we fall back to the existing multimodal envelope so the
behaviour is at worst the pre-fix status quo. Temp screenshot files
are cleaned up unconditionally in a finally block — even on aux call
failure — to avoid leaving residue under cache/vision/.
The end-to-end regression for #24015 is added in the next commit.
Bug 2 (capture_after=True loses app context):
_maybe_follow_capture called backend.capture(mode='som') with no app=,
causing cua-driver to capture the frontmost window instead of the app
targeted by the preceding capture/focus_app. Fix: track _last_app on
CuaDriverBackend and thread it through the follow-up capture call so
the same app is re-captured regardless of which window has OS focus.
Bug 5 (element labels stripped in capture results):
_ELEMENT_LINE_RE matched the classic ' - [N] AXRole "label"' format
but not the '[N] AXRole (order) id=Label' format introduced in
cua-driver v0.1.6. All element labels were silently dropped as empty
strings, making element identification impossible.
Fix: extend regex to capture both group(3) (quoted label) and group(4)
(id= label), and update _parse_elements_from_tree to use group(4) as
fallback. Both old and new cua-driver output now produce populated
UIElement.label values.
focus_app() now also sets _last_app so that capture_after= on any
subsequent action re-targets the focused app.
5 new regression tests added.
Part of #24170 (bugs 1 and 3/4 addressed separately).
Bug 3: The cua_backend type_text() method called MCP tool 'type_text_chars'
which does not exist in current cua-driver. Changed to 'type_text' which is
the correct MCP tool name.
Bug 4: The drag() method returned a hardcoded 'not supported' error even
though cua-driver exposes a 'drag' MCP tool. Implemented proper drag
dispatching with coordinate-based and element-based targeting.
Added dispatch-level validation for drag to ensure from/to coordinates
or elements are provided before calling any backend.
Fixes#24170 (bugs 3 and 4)
Replace with for all literal-tuple
membership tests. Set lookup is O(1) vs O(n) for tuple — consistent
micro-optimization across the codebase.
608 instances fixed via `ruff --fix --unsafe-fixes`, 0 remaining.
133 files, +626/-626 (net zero).
Extends the cua-driver computer-use backend to drive backgrounded macOS
windows without stealing keyboard or mouse focus from the foreground app.
All changes target the cua-driver MCP backend and the shared dispatcher.
## cua_backend.py
**Window-aware capture**: capture() now calls list_windows + get_window_state
instead of the removed capture tool. Prefers structuredContent.windows
(MCP 2024-11-05+ cua-driver) for zero-parse window enumeration; falls back
to regex-parsed text for older builds. Stores the selected (pid, window_id)
as sticky context so subsequent action calls do not need a redundant round-trip.
**Action routing**: click/scroll/type_text/key all carry the sticky pid
(and window_id for element-indexed clicks). type_text routes through
type_text_chars (individual key events) rather than AX attribute write --
WebKit AXTextFields reject attribute writes from backgrounded processes.
**Key parsing**: _parse_key_combo splits cmd+s-style strings into
(key, [modifiers]) and routes to hotkey (modifier present) or
press_key (bare key) -- cua-driver actual tool names.
**set_value method**: new set_value(value, element) calls the cua-driver
set_value MCP tool. For AXPopUpButton / HTML select in a backgrounded Safari,
AXPress opens the native macOS popup which closes immediately when the app is
non-frontmost; set_value AX-presses the matching child option directly
(no menu required, no focus steal).
**focus_app**: reimplemented as a pure window-selector (enumerates
list_windows, sets sticky pid/window_id) without ever raising the window
or stealing focus.
**list_apps**: fixed tool name from listApps to list_apps; handles plain-text
response via regex when structured data is absent.
**Structured-content extraction**: _extract_tool_result now surfaces
structuredContent from MCP results, enabling the list_windows window array
without text parsing.
**Helpers**: _parse_windows_from_text, _parse_elements_from_tree,
_split_tree_text, _parse_key_combo extracted as module-level functions.
## schema.py
Added set_value to the action enum with a description explaining when to
prefer it over click (select/popup elements, sliders, no focus steal).
Added value field for set_value payloads.
## tool.py
Routed set_value action through _dispatch to backend.set_value.
Added set_value to _DESTRUCTIVE_ACTIONS (approval-gated).
Fixed MIME-type detection in _capture_response: cua-driver may return
JPEG; detect from base64 magic bytes (/9j/ -> image/jpeg, else image/png)
rather than hardcoding image/png.
## agent/display.py + run_agent.py
Guard _detect_tool_failure and result-preview logic against non-string
function_result values: multimodal tool results (dicts with _multimodal=True)
are not string-sliceable; treat them as successes and fall back to str()
for length/preview.
Background macOS desktop control via cua-driver MCP — does NOT steal the
user's cursor or keyboard focus, works with any tool-capable model.
Replaces the Anthropic-native `computer_20251124` approach from the
abandoned #4562 with a generic OpenAI function-calling schema plus SOM
(set-of-mark) captures so Claude, GPT, Gemini, and open models can all
drive the desktop via numbered element indices.
- `tools/computer_use/` package — swappable ComputerUseBackend ABC +
CuaDriverBackend (stdio MCP client to trycua/cua's cua-driver binary).
- Universal `computer_use` tool with one schema for all providers.
Actions: capture (som/vision/ax), click, double_click, right_click,
middle_click, drag, scroll, type, key, wait, list_apps, focus_app.
- Multimodal tool-result envelope (`_multimodal=True`, OpenAI-style
`content: [text, image_url]` parts) that flows through
handle_function_call into the tool message. Anthropic adapter converts
into native `tool_result` image blocks; OpenAI-compatible providers
get the parts list directly.
- Image eviction in convert_messages_to_anthropic: only the 3 most
recent screenshots carry real image data; older ones become text
placeholders to cap per-turn token cost.
- Context compressor image pruning: old multimodal tool results have
their image parts stripped instead of being skipped.
- Image-aware token estimation: each image counts as a flat 1500 tokens
instead of its base64 char length (~1MB would have registered as
~250K tokens before).
- COMPUTER_USE_GUIDANCE system-prompt block — injected when the toolset
is active.
- Session DB persistence strips base64 from multimodal tool messages.
- Trajectory saver normalises multimodal messages to text-only.
- `hermes tools` post-setup installs cua-driver via the upstream script
and prints permission-grant instructions.
- CLI approval callback wired so destructive computer_use actions go
through the same prompt_toolkit approval dialog as terminal commands.
- Hard safety guards at the tool level: blocked type patterns
(curl|bash, sudo rm -rf, fork bomb), blocked key combos (empty trash,
force delete, lock screen, log out).
- Skill `apple/macos-computer-use/SKILL.md` — universal (model-agnostic)
workflow guide.
- Docs: `user-guide/features/computer-use.md` plus reference catalog
entries.
44 new tests in tests/tools/test_computer_use.py covering schema
shape (universal, not Anthropic-native), dispatch routing, safety
guards, multimodal envelope, Anthropic adapter conversion, screenshot
eviction, context compressor pruning, image-aware token estimation,
run_agent helpers, and universality guarantees.
469/469 pass across tests/tools/test_computer_use.py + the affected
agent/ test suites.
- `model_tools.py` provider-gating: the tool is available to every
provider. Providers without multi-part tool message support will see
text-only tool results (graceful degradation via `text_summary`).
- Anthropic server-side `clear_tool_uses_20250919` — deferred;
client-side eviction + compressor pruning cover the same cost ceiling
without a beta header.
- macOS only. cua-driver uses private SkyLight SPIs
(SLEventPostToPid, SLPSPostEventRecordTo,
_AXObserverAddNotificationAndCheckRemote) that can break on any macOS
update. Pin with HERMES_CUA_DRIVER_VERSION.
- Requires Accessibility + Screen Recording permissions — the post-setup
prints the Settings path.
Supersedes PR #4562 (pyautogui/Quartz foreground backend, Anthropic-
native schema). Credit @0xbyt4 for the original #3816 groundwork whose
context/eviction/token design is preserved here in generic form.
Extends the cua-driver computer-use backend to drive backgrounded macOS
windows without stealing keyboard or mouse focus from the foreground app.
All changes target the cua-driver MCP backend and the shared dispatcher.
## cua_backend.py
**Window-aware capture**: capture() now calls list_windows + get_window_state
instead of the removed capture tool. Prefers structuredContent.windows
(MCP 2024-11-05+ cua-driver) for zero-parse window enumeration; falls back
to regex-parsed text for older builds. Stores the selected (pid, window_id)
as sticky context so subsequent action calls do not need a redundant round-trip.
**Action routing**: click/scroll/type_text/key all carry the sticky pid
(and window_id for element-indexed clicks). type_text routes through
type_text_chars (individual key events) rather than AX attribute write --
WebKit AXTextFields reject attribute writes from backgrounded processes.
**Key parsing**: _parse_key_combo splits cmd+s-style strings into
(key, [modifiers]) and routes to hotkey (modifier present) or
press_key (bare key) -- cua-driver actual tool names.
**set_value method**: new set_value(value, element) calls the cua-driver
set_value MCP tool. For AXPopUpButton / HTML select in a backgrounded Safari,
AXPress opens the native macOS popup which closes immediately when the app is
non-frontmost; set_value AX-presses the matching child option directly
(no menu required, no focus steal).
**focus_app**: reimplemented as a pure window-selector (enumerates
list_windows, sets sticky pid/window_id) without ever raising the window
or stealing focus.
**list_apps**: fixed tool name from listApps to list_apps; handles plain-text
response via regex when structured data is absent.
**Structured-content extraction**: _extract_tool_result now surfaces
structuredContent from MCP results, enabling the list_windows window array
without text parsing.
**Helpers**: _parse_windows_from_text, _parse_elements_from_tree,
_split_tree_text, _parse_key_combo extracted as module-level functions.
## schema.py
Added set_value to the action enum with a description explaining when to
prefer it over click (select/popup elements, sliders, no focus steal).
Added value field for set_value payloads.
## tool.py
Routed set_value action through _dispatch to backend.set_value.
Added set_value to _DESTRUCTIVE_ACTIONS (approval-gated).
Fixed MIME-type detection in _capture_response: cua-driver may return
JPEG; detect from base64 magic bytes (/9j/ -> image/jpeg, else image/png)
rather than hardcoding image/png.
## agent/display.py + run_agent.py
Guard _detect_tool_failure and result-preview logic against non-string
function_result values: multimodal tool results (dicts with _multimodal=True)
are not string-sliceable; treat them as successes and fall back to str()
for length/preview.
Background macOS desktop control via cua-driver MCP — does NOT steal the
user's cursor or keyboard focus, works with any tool-capable model.
Replaces the Anthropic-native `computer_20251124` approach from the
abandoned #4562 with a generic OpenAI function-calling schema plus SOM
(set-of-mark) captures so Claude, GPT, Gemini, and open models can all
drive the desktop via numbered element indices.
- `tools/computer_use/` package — swappable ComputerUseBackend ABC +
CuaDriverBackend (stdio MCP client to trycua/cua's cua-driver binary).
- Universal `computer_use` tool with one schema for all providers.
Actions: capture (som/vision/ax), click, double_click, right_click,
middle_click, drag, scroll, type, key, wait, list_apps, focus_app.
- Multimodal tool-result envelope (`_multimodal=True`, OpenAI-style
`content: [text, image_url]` parts) that flows through
handle_function_call into the tool message. Anthropic adapter converts
into native `tool_result` image blocks; OpenAI-compatible providers
get the parts list directly.
- Image eviction in convert_messages_to_anthropic: only the 3 most
recent screenshots carry real image data; older ones become text
placeholders to cap per-turn token cost.
- Context compressor image pruning: old multimodal tool results have
their image parts stripped instead of being skipped.
- Image-aware token estimation: each image counts as a flat 1500 tokens
instead of its base64 char length (~1MB would have registered as
~250K tokens before).
- COMPUTER_USE_GUIDANCE system-prompt block — injected when the toolset
is active.
- Session DB persistence strips base64 from multimodal tool messages.
- Trajectory saver normalises multimodal messages to text-only.
- `hermes tools` post-setup installs cua-driver via the upstream script
and prints permission-grant instructions.
- CLI approval callback wired so destructive computer_use actions go
through the same prompt_toolkit approval dialog as terminal commands.
- Hard safety guards at the tool level: blocked type patterns
(curl|bash, sudo rm -rf, fork bomb), blocked key combos (empty trash,
force delete, lock screen, log out).
- Skill `apple/macos-computer-use/SKILL.md` — universal (model-agnostic)
workflow guide.
- Docs: `user-guide/features/computer-use.md` plus reference catalog
entries.
44 new tests in tests/tools/test_computer_use.py covering schema
shape (universal, not Anthropic-native), dispatch routing, safety
guards, multimodal envelope, Anthropic adapter conversion, screenshot
eviction, context compressor pruning, image-aware token estimation,
run_agent helpers, and universality guarantees.
469/469 pass across tests/tools/test_computer_use.py + the affected
agent/ test suites.
- `model_tools.py` provider-gating: the tool is available to every
provider. Providers without multi-part tool message support will see
text-only tool results (graceful degradation via `text_summary`).
- Anthropic server-side `clear_tool_uses_20250919` — deferred;
client-side eviction + compressor pruning cover the same cost ceiling
without a beta header.
- macOS only. cua-driver uses private SkyLight SPIs
(SLEventPostToPid, SLPSPostEventRecordTo,
_AXObserverAddNotificationAndCheckRemote) that can break on any macOS
update. Pin with HERMES_CUA_DRIVER_VERSION.
- Requires Accessibility + Screen Recording permissions — the post-setup
prints the Settings path.
Supersedes PR #4562 (pyautogui/Quartz foreground backend, Anthropic-
native schema). Credit @0xbyt4 for the original #3816 groundwork whose
context/eviction/token design is preserved here in generic form.
