fix(bridge): make drag a real pointer gesture so it drives JS drag libraries - #142
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…braries `drag` dispatched the HTML5 DragEvent sequence plus a single `mousedown`, with no `mousemove` stream and no `mouseup`, then returned `ok: true` unconditionally. That drives `draggable="true"` handlers, but not the other family of drag implementation: dnd-kit, sortable.js, interact.js and react-dnd's mouse backend never see DragEvents. They activate on `mousedown`, track *repeated* `mousemove`/`pointermove` events on `document` behind a small distance threshold, and commit on `mouseup`. A press with no movement and no release cannot activate them, so `tauri-pilot drag` against such an app did nothing and reported success — the worst outcome for an agent asserting on the result. The gesture now: * presses the deepest node under the start point (`elementFromPoint`) rather than the resolved element — library listeners commonly sit on an inner handle or card, and events only bubble upward, so pressing the container misses them; * streams interpolated `mousemove`/`pointermove` events on `document` with `buttons: 1`, clearing distance thresholds (`document` because a `position: fixed` ancestor can otherwise break pointer capture in WKWebView); * emits the HTML5 sequence exactly as before, so native handlers do not regress; * releases with `mouseup`/`pointerup`, then waits for the app to settle, since a library drop commonly triggers async state/network work before the DOM updates. `steps` (1–60, default 12), `stepDelayMs` (default 16) and `settleMs` (default 250) tune it. `drag` is now async; the eval wrapper already awaits results, so the protocol is unchanged. The result gains `from`, `to`, `steps` and `html5DropHandled` (true when a handler called `preventDefault()` on the drop). `ok` still means only that the gesture was delivered — nothing observable from outside can prove a library handled a drop — and the docs now say so instead of implying success. PointerEvent is used only when the constructor exists, so a WebView without it degrades to mouse-only events rather than throwing. Verified against a real Tauri v2 + React app on macOS (WKWebView) using @dnd-kit/core 6.3.1 with MouseSensor and a 6px activation distance: before this change `tauri-pilot drag <source> <target>` printed `ok` and changed nothing; after it, the dragged item lands in the drop zone and the resulting row is present in the app's SQLite database.
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Important Approval pendingCodeRabbit has no unresolved comments, but it could not review the latest commit because the review limit was reached. Follow the review guidance in this comment to continue. 📝 WalkthroughWalkthroughThe ChangesDrag gesture delivery
Estimated code review effort: 3 (Moderate) | ~25 minutes Merge Risk: 🟡 Moderate · up to This PR changes drag into an asynchronous pointer gesture with configurable timing. At the current head, zero-valued steps can be interpreted differently between layers, allowing long-delay drags to exceed the command timeout, while one timing test can fail under normal scheduler delays. These are bounded but concrete merge-readiness risks that should be corrected or explicitly accepted before merging. Suggested reviewers: Sequence Diagram(s)sequenceDiagram
participant Client
participant MCP
participant RustHandler
participant Bridge
participant DOM
Client->>MCP: invoke drag with gesture parameters
MCP->>RustHandler: forward drag params
RustHandler->>Bridge: evaluate drag with calculated timeout
Bridge->>DOM: dispatch press events
loop configured steps
Bridge->>DOM: dispatch hit-tested pointermove and mousemove events
end
Bridge->>DOM: dispatch HTML5 drag and drop events
Bridge->>DOM: dispatch release events
Bridge-->>Client: return gesture metadata and drop status
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✅ Passed checks (4 passed)
Full details: Description checkExplanation The description provides detailed problem, motivation, implementation, compatibility, testing, live verification, and documentation context. It does not use the template headings exactly and does not include the template checklist, but it is substantially complete and directly related to the changes. Full details: Docstring CoverageExplanation Docstring coverage is 79.17% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 24 functions across 4 files. (3 skipped: 3 unsupported.) Comment |
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Inline comments:
In `@crates/tauri-plugin-pilot/js/bridge.js`:
- Around line 653-662: Update dispatchPointerPair in
crates/tauri-plugin-pilot/js/bridge.js so each available PointerEvent is
dispatched before its paired MouseEvent, preserving pointerdown→mousedown,
pointermove→mousemove, and pointerup→mouseup ordering. Update the affected drag
assertions in crates/tauri-plugin-pilot/js/bridge.drag.test.mjs at lines 313-317
and 348-351 to expect this order.
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The bug is real and the direction is right, but I can't take this as-is.
I checked main: drag sends a single mousedown with no move stream and no release, so dnd-kit and the rest genuinely cannot activate on it. Your tests load the real bridge.js instead of a reimplementation, all 17 pass here, CI is green, and wrap_script does await(script) so the async change is safe on the Rust side. That part holds up.
What blocks it is that the bridge already has the helper you rewrote, and the rewrite is worse than the original on four counts. On top of that the move dispatch target is wrong in a way that happens to work for dnd-kit specifically and fails for a lot of other things. Details inline.
Two things about the description before the code:
#141 is the Dependabot js-yaml bump, not a drag issue. The test file cites it three times as if it were the tracking issue for this work.
The position: fixed / pointer capture justification for dispatching moves on document doesn't hold up. Nothing here calls setPointerCapture, and CSS positioning has no effect on event dispatch. If there was a real symptom behind that choice I'd like to know what it was, because the fix for it is probably not this.
cubic's notes on the pointer/mouse ordering, the missing composed, the timeout budget and the trailing sleep are all valid. The first two fall out of the first inline comment below.
Replaces `dispatchPointerPair` with a thin wrapper over the existing `dispatchPointerEvent`. That fixes four things at once: pointer events now precede their compatibility mouse events as the spec (and `click()`) has them, `composed: true` lets the press escape a shadow root, a WebView without the `PointerEvent` constructor still gets pointer-typed events instead of nothing, and a cancelled pointer event suppresses its mouse counterpart. The unused `accepted` return is gone with it. The press target is now gated on containment. `elementFromPoint` hands back whatever is on top, so a toast or backdrop over the source would take the press while `drag` still returned ok — the false green this change exists to remove. Moves and the release are hit-tested per point instead of going to `document`. Dispatching on `document` gives the event a propagation path of `[window, document]` and nothing else, so listeners on elements between the pressed node and the document never fire; React 17+ delegates on its root container, not on `document`. They still bubble to the document-level listeners dnd-kit and friends install. The step delay no longer runs after the last move, where it separates nothing and only pushes the drop sequence back. `steps`, `stepDelayMs` and `settleMs` are declared in the MCP drag schema and forwarded, which the docs already claimed. The plugin sizes the eval timeout from them, so a gesture tuned past 10s is no longer cut short by the channel while the bridge is still mid-drag. Drops the `mpiton#141` references from the test file — that issue is a js-yaml dependabot bump, not this bug.
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Inline comments:
In `@crates/tauri-plugin-pilot/js/bridge.drag.test.mjs`:
- Line 527: Update the timing assertion in the drag gesture test to remove the
wall-clock upper bound on elapsed time. Use fake timers or inspect the scheduled
delay calls to verify the expected two-delay behavior without relying on real
event-loop completion timing.
In `@crates/tauri-plugin-pilot/src/handler.rs`:
- Line 76: Update the steps calculation in the handler to map an input of zero
to the bridge fallback value 12 before applying the upper clamp, while retaining
the 1–60 bounds for other values. Add a timeout test covering zero steps with
stepDelayMs set to 1000 and verify behavior matches the bridge path.
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`bridge.js` sends any `steps` below 1 back to its default of 12, but the Rust budget clamped it to 1. A `steps: 0, stepDelayMs: 1000` call therefore got a 10s channel while the bridge still had 12s of move delays to run, which is the same dropped-result failure the budget was added to prevent. Zero is now mapped to 12 before the upper clamp. The trailing-delay test recorded wall-clock time with an upper bound, which a paused event loop can blow through on a correct gesture. It now captures what the gesture schedules instead and asserts the exact sequence of sleeps, which is deterministic and pins the settle as well.
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`bridge.js` runs steps/stepDelayMs/settleMs through `Number()`, so a numeric string or a fractional value is a real setting there. `drag_eval_timeout` read them with `as_u64`, which returns None for both, so `stepDelayMs: "1000"` on a 60-step gesture budgeted the 10 s floor against a 60 s drag and timed the channel out mid-drag. Mirror the coercion instead: parse numeric strings, keep fractions, floor only `steps`.
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`Number("0x3e8")` is 1000, so a hex literal is a real one-second step delay in
the bridge while `f64::from_str` rejected it and the budget dropped back to the
10 s floor. Same failure the decimal-string fix addressed, one string form
further out. Also corrects the coercion note above `field`: `Number(true)` is
1, not 0.
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`Number()` puts no width limit on `0x`/`0o`/`0b` literals, and `steps` clamps
to 60 afterwards, so parsing into u32 sent `steps: "0xFFFFFFFFFF"` back to the
default of 12 while the bridge ran the full 60. Accumulate into f64 instead,
and reject a bare prefix the way `Number("0x")` does.
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Problem
dragdispatches the HTML5 DragEvent sequence plus a singlemousedown— nomousemovestream, nomouseup— and then returnsok: trueunconditionally.That works for
draggable="true"handlers. It cannot work for the other family of drag implementation: dnd-kit, sortable.js, interact.js and react-dnd's mouse backend never receive DragEvents. They activate onmousedown, then track repeatedmousemove/pointermoveevents ondocumentbehind a small distance threshold, and commit onmouseup. A press with no movement and no release cannot activate them.So on a React app using dnd-kit,
tauri-pilot drag @e5 @e8printedokand changed nothing. For an agent — the primary audience for this tool — a false green is worse than an error, because the assertion that follows is written against a UI that never moved.What changed
bridge.jsdrag()now emits a gesture both families can see:document.elementFromPoint) instead of the resolved element. Library listeners commonly sit on an inner handle or card, and DOM events only bubble upward, so pressing the resolved container never reaches them. This was the difference between "no events fire" and "drag activates" in my testing.mousemove/pointermoveevents ondocumentwithbuttons: 1, so distance thresholds clear and listeners do not treat the move as a hover.documentbecause aposition: fixedancestor can otherwise break pointer capture in WKWebView.dragstart→dragleave→dragenter→dragover→drop→dragend) on the same elements as before, so native handlers do not regress.mouseup/pointerup, then waitssettleMsbefore returning, because a library drop commonly kicks off async state/network work before the DOM reflects it.New optional params:
steps(1–60, default 12),stepDelayMs(default 16),settleMs(default 250). The CLI surface is unchanged and uses the defaults.dragis nowasync.EvalEngine::wrap_scriptalready doesawait (script), andscreenshotis async already, so the protocol and Rust side are untouched.Honesty about the return value
oknow documents what it actually means: the gesture was delivered. Nothing observable from outside the app can prove a library handled a drop, so the docs tell callers to assert the effect instead of trustingok.The one signal the bridge can observe is added:
html5DropHandledis true when a handler calledpreventDefault()on thedropevent. The result also echoesfrom,toandsteps.Compatibility
PointerEventis only constructed when the global exists, so a WebView without it degrades to mouse-only events instead of throwing.elementFromPointonce to find the press target, where before it made no such call. The existing test that asserted "skips elementFromPoint" was updated to assert the press-target lookup instead.Tests
bridge.drag.test.mjsgoes from 8 to 17 tests, all against the realbridge.js:buttons: 1html5DropHandledtrue/falsePointerEventstepsclamping for missing/zero/negative/non-numeric/fractional/oversized inputfrom/toLive verification
Tested against a real Tauri v2 + React desktop app on macOS (WKWebView),
@dnd-kit/core6.3.1 withMouseSensorand a 6px activation distance, dragging a card from aposition: fixeddrawer into a drop zone:tauri-pilot drag '[aria-roledescription="draggable"]' '.hb-slot.is-empty'→ok, zero rows written, UI unchanged.Also confirmed via the app's own drag instrumentation that the drop route received a valid pointer position, which it did not before.
Docs
docs/reference/cli.mdexplains both event families, the press-target rule, the tuning params, and whatokdoes and does not mean.README.md,SKILL.mdandCHANGELOG.mdupdated.Summary by cubic
Makes
draga real pointer gesture so it drives JS drag libraries (dnd-kit, sortable.js, interact.js, react-dnd) as well as HTML5 native drag. Previouslydragemitted only the HTML5 DragEvent sequence plus onemousedownand returnedok: trueeven when nothing moved.pointermove/mousemovewithbuttons: 1, each hit-tested at its own point, then releases; pointer events precede their mouse counterparts and the HTML5 sequence is unchanged.steps(1–60, default 12),stepDelayMs(default 16), andsettleMs(default 250) via JSON-RPC and MCP;dragis now async and the Rust eval timeout is sized from the tunables, mirroring the bridge's coercion and clamping so tuned gestures aren't cut short.from,to,steps, andhtml5DropHandled;okmeans the gesture was delivered, so assert the effect separately.MouseEvents whenPointerEventis unavailable; offset and scroll-into-view behavior are unchanged.Migration
window.__PILOT__.dragcallers must await it; setsettleMsorstepDelayMsin tests to control timing.Written for commit 97e1a8e. Summary will update on new commits.
Summary by CodeRabbit
New Features
Bug Fixes
Documentation