feat(canvas): comment-mode annotation overlay with element and text targets#3599
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Canvas generation previously required the agent to regenerate and emit the entire React source every turn. Add a canvas_checkout / canvas_publish local tool pair (available to both the Claude and Codex adapters) that moves the file I/O tool-side: checkout writes the live source to a scratch path and records the base version, the agent applies targeted edits with its native file tools, and publish reads the file from disk and appends a version — refusing when the canvas moved past the checkout base (concurrent edit or undo) instead of clobbering it. The generation prompt now routes through checkout → edit → publish and no longer embeds the current source. Storage stays wholesale full-file snapshots; a server-side base_version check on the desktop-fs PATCH remains a follow-up. Generated-By: PostHog Code Task-Id: 2b3d176e-3023-41d2-92e8-81eda7c12a8c
…as action canvas_publish now calls the desktop-fs canvas action, which owns version composition server-side, passing the checkout's version as expected_current_version_id so a stale publish is rejected atomically (409 version_conflict) instead of guarded by a non-atomic tool-side check-then-PATCH. Deletes the tool-side compose logic and the raw meta PATCH; backends predating the guard field ignore it and publish unguarded, so the tool degrades gracefully. Server side: PostHog/posthog#72365. Generated-By: PostHog Code Task-Id: 2b3d176e-3023-41d2-92e8-81eda7c12a8c
…ools The "do not regenerate wholesale" phrasing in the checkout tool description, its runtime message, and the generation prompt warned against a workflow a fresh agent never sees, and could bias against legitimately large rewrites. The one forward-looking economy nudge (prefer targeted edits over rewriting the whole file for a small change) stays in the authoring contract in canvasTemplates.ts, stated once. Generated-By: PostHog Code Task-Id: 2b3d176e-3023-41d2-92e8-81eda7c12a8c
…argets Canvas feedback was whole-document chat: describing the target in prose was the only way to point at something. Add a comment mode to freeform canvases: a host-authored overlay in the sandbox iframe captures element clicks and text selections as structured, LLM-locatable targets (stable-attribute selector, bounded text, attributes), queued annotations render as numbered pins in the canvas and editable comment chips above the composer, and on submit they fold into the generation instruction as a numbered [Annotations] block the agent resolves into targeted edits of the checked-out scratch file. Selector inference follows the toolbar's product-tours approach (stable attribute allowlist, nth-of-type fallback) in a dependency-free form — precision is secondary since the consumer is the agent locating spots in source it wrote itself. Generated-By: PostHog Code Task-Id: 2b3d176e-3023-41d2-92e8-81eda7c12a8c
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Problem
Canvas feedback is whole-document chat: describing the target in prose is the only way to point at something on the rendered canvas. There is no structured "annotate a specific part of the artifact" primitive.
Why
The second phase of making canvas iteration surgical (stacked on #3594's workspace-file editing): structured annotations that map onto targeted edits, and groundwork for plan-canvas review loops. Direction discussed in the linked task thread.
Changes
sandboxRuntime.ts, outside#root— agent-authored canvas code never sees it). Toolbar toggle → crosshair + hover highlight; click captures an element target, drag-select captures a text-range target. Targets are LLM-locatable rather than machine-precise: stable-attribute selector (allowlist + nth-of-type fallback, following the toolbar's product-tours inference in dependency-free form), bounded text snippet, attributes.canvasAnnotationsStore, per-canvas).[Annotations]block; the agent resolves each into a targeted edit of the checked-out scratch file via the feat(canvas): edit canvases as scratch files via canvas_checkout / canvas_publish #3594 loop. Two new schema-validated postMessage types each way; no new backend.How did you test this code?
vitest: new[Annotations]prompt-block test; full canvas suites pass (core 94, ui 147).tsc --noEmitclean on@posthog/core/@posthog/ui;biomeclean on touched dirs.Automatic notifications
Created with PostHog Code