[BUG] postMessageToWebview unhandled rejection; dispose() not idempotent

[0xMink]

Problem (one or two sentences)

Two reliability issues in src/core/webview/ClineProvider.ts:

1. postMessageToWebview() does not catch rejections from this.view?.webview.postMessage(...). If the webview is disposed before delivery, this can surface as an unhandled promise rejection.
2. dispose() is not idempotent. If called multiple times (for example during rapid deactivation/reload), it repeats cleanup work that should run once.

Context (who is affected and when)

Occurs during extension deactivation, reload, or when the panel is closed while messages are in flight. Can produce noisy errors in the Developer Tools console and/or output channel.

Reproduction steps

1. Environment: Any OS, Roo Code v3.47.3.
2. Start a task, then immediately close the Roo Code panel or reload the VS Code window.
3. Open Developer Tools console (Help → Toggle Developer Tools → Console) and observe errors.
4. For dispose: trigger extension deactivation twice in quick succession (e.g., rapid reload).

Expected result

postMessageToWebview() drops messages safely if the webview is disposed. dispose() is idempotent; subsequent calls are no-ops.

Actual result

postMessageToWebview() can produce unhandled promise rejections after disposal. dispose() re-executes cleanup on repeated calls.

Variations tried (optional)

N/A

App Version

v3.47.3

API Provider (optional)

None

Model Used (optional)

N/A

Roo Code Task Links (optional)

No response

Relevant logs or errors (optional)

Unhandled promise rejection when webview.postMessage() is called after the webview has been disposed (error text varies).

[roomote]

I've analyzed this issue and here's my proposed implementation plan:

File: src/core/webview/ClineProvider.ts

1. Add a isDisposed flag (class property)

Add private isDisposed = false alongside the other private properties (around line 152). This flag will be used by both fixes.

2. Make dispose() idempotent (line 579)

At the top of dispose(), add an early-return guard:

async dispose() {
    if (this.isDisposed) {
        return
    }
    this.isDisposed = true
    // ... rest of existing cleanup
}

This ensures repeated calls are safe no-ops.

3. Guard postMessageToWebview() against post-disposal rejections (line 1082)

Wrap the postMessage call in a try/catch and add a disposed check:

public async postMessageToWebview(message: ExtensionMessage) {
    if (this.isDisposed) {
        return
    }
    try {
        await this.view?.webview.postMessage(message)
    } catch {
        // Webview was disposed before the message could be delivered -- safe to ignore.
    }
}

The isDisposed check avoids unnecessary work, and the try/catch handles the race where the webview is disposed between the check and delivery.

4. Add tests

Add a test file src/core/webview/__tests__/ClineProvider.dispose.spec.ts covering:

• dispose() is idempotent (second call is a no-op)
• postMessageToWebview() silently drops messages after disposal
• postMessageToWebview() catches rejections from a disposed webview

This is a minimal, focused change that addresses both reported problems without altering any other behavior.

Please mention @roomote in a comment saying that you approve this plan, and I'll proceed with the implementation.