fix(canvas): keep unpublished improvements local

.github/extensions/replica-prototype/README.md

@@ -70,6 +70,8 @@ Contributors can load uncommitted changes from a local Replica checkout with `co
 
 ## Pick & polish
 
+New improvements remain local until their captured source matches a successful published Build, including on branches with an older Build. Target selection captures the source without changing the real Git index. Capture failures and older notes without provenance still allow local use but cannot synchronize. Once uploaded, later changes retain the original Build identity and remain private owner notes.
+
 **Fix all** invokes the bundled, model-discoverable [`/replica-pick-and-polish` skill](skills/replica-pick-and-polish/SKILL.md) with the verified checkout, branch, batch ID, and thread count. Notes, conversation history, and images are retrieved separately from the immutable batch. When the skill is missing or disabled, or the runtime has no skill catalog, the request includes the same bundled procedure inline. Catalog or fallback-file errors stop preparation without sending work or leaving a batch awaiting results. See the [Pick & polish guide](../../../hub/docs/prototype-canvas.md#pick--polish) for saved-note and recovery behavior.
 
 ## Learnings
@@ -268,7 +270,7 @@ Without a usable connection, the canvas offers a dismissible dialog once per ope
 
 Seven-day access tokens renew automatically while repository access remains valid and the connection has not been revoked or inactive for 30 days. Focus and user-initiated Hub actions count as activity; background polling and renewal do not. Expiry or revocation requires approval again. Temporary outages keep the preview usable and preserve saved credentials. Older connections keep their original expiry and need one new approval to become renewable. **Disconnect Hub** revokes the selected connection; you can also revoke it at `/canvas/connections` in Hub. Switching Hubs does not revoke an earlier connection.
 
-The canvas follows branch changes. If Hub has not discovered the branch, the repository remains connected; push the branch and wait for discovery to use its Builds and reviews. Once Hub imports a successful Build of the current checkout, the canvas automatically registers eligible prototypes using the branch name as the initial title. Existing metadata is preserved. Use **Edit metadata** in **Hub** to change the title or description afterward. Registration requires write access and Hub's branch eligibility checks; errors appear in the shared critical banner and status polling retries automatically. Updated Hub APIs supply a `registrationReason` code explaining missing write access, excluded branches, missing remote heads, or branch authorship requirements. Unknown codes and older Hubs retain a generic error; independently verified permission and remote-ref facts can supply a specific explanation. Installing the extension does not deploy the updated Hub API.
+The canvas follows branch changes. If Hub has not discovered the branch, the repository remains connected and comments can be saved locally; push the branch and wait for discovery to use its published Builds and reviews. Once Hub imports a successful Build of the current checkout, the canvas automatically registers eligible prototypes using the branch name as the initial title. Existing metadata is preserved. Use **Edit metadata** in **Hub** to change the title or description afterward. Registration requires write access and Hub's branch eligibility checks; errors appear in the shared critical banner and status polling retries automatically. Updated Hub APIs supply a `registrationReason` code explaining missing write access, excluded branches, missing remote heads, or branch authorship requirements. Unknown codes and older Hubs retain a generic error; independently verified permission and remote-ref facts can supply a specific explanation. Installing the extension does not deploy the updated Hub API.
 
 For a Hub started in [local development mode](https://github.com/github/replica/blob/main/hub/docs/local-development.md), open Copilot in Hub's `.local/prototypes/example` checkout and pass `"repository": "local/example"` when opening the canvas. Local repository hints only apply to matching checkouts under `.local/prototypes/` with a loopback Hub origin; they cannot redirect a remote checkout to another Hub repository. Start that example's dev server on a port reachable from the canvas before opening it.
 
@@ -286,7 +288,9 @@ Pending commit-and-publish requests remain deduplicated across verified descenda
 
 Copilot uses the existing push workflow, not manual Actions dispatch or another publishing path. It follows `refresh_status`, registers discovered branches with `update_metadata`, and preserves saved metadata. If it stops before pushing, it calls `report_publish_result` with the request target and a `blocked`, `canceled`, or `failed` outcome so the canvas stops waiting and offers a retry. A later push of the current HEAD clears that failure so the canvas follows the new workflow and Build. The action rejects other canvases, targets, or modes, and any request whose push was already observed. It waits for Hub's imported Build matching the pushed commit and returns its exact URL. An older Build or Actions success alone is not enough. The local preview stays open. Entry-page checks still apply; incomplete landing-page verification is reported, not silently repaired and republished.
 
-The canvas header uses Hub's review controls: **Add a comment** sits beside a comment count with unread state, and selecting the count opens the dedicated comments sidebar. The sidebar includes Hub's search, build/page/participant/read/resolved filters, pin visibility control, conversation rows, and thread view; the **Hub** panel remains focused on connection, prototype metadata, and publication state. Select a preview marker or conversation row to open the thread beside its target and reply without leaving the canvas. Markers use the same participant avatars, overflow, unread, resolved, focus, and accessible-label behavior as Hub. When the local checkout matches the imported Build's exact commit, **Add a comment** supports the same element and highlighted-area targets as Hub and saves the new thread directly to Hub. You can also reply, edit or delete your own messages, react, and resolve or reopen threads. Live changes arrive over Hub's review channel, with periodic refresh if that connection is unavailable. Hub credentials stay in the extension process and are never sent to the local preview.
+**Add a comment** targets an element or highlighted area. Comments on unpublished changes stay on the author's device until a matching Build is published; comments on a clean checkout of the published Build save directly to Hub. See [local preview comments](../../../hub/docs/prototype-canvas.md#local-preview-comments) for requirements, storage and recovery.
+
+The header's comment count opens a sidebar with Hub's search, filters, unread state and pin visibility controls. Select a marker or row to open its conversation beside the target. Published conversations support replies, edits, deletion, reactions and resolution. Hub sends live updates, with periodic refresh when unavailable. The **Hub** panel remains focused on connection, metadata and publication. Hub credentials never reach the local preview.
 
 Open an already-running unauthenticated loopback prototype in this canvas. The extension's per-panel reverse proxy supplies its bundled bridge to ordinary Vite dev/preview and static HTML servers. Multiple prototypes, including servers in the same checkout, have independent proxy ports and lifecycles. Closing a panel stops only its proxy.