Add external URI opener for Claude Code VSCode extension support

[Copilot]

Extension only worked when Claude Code ran in integrated terminal via PLANNOTATOR_BROWSER env var injection. Failed to intercept URLs when Claude Code ran as a VSCode extension using vscode.env.openExternal().

Changes

External URI opener registration (src/extension.ts)

• Registers window.registerExternalUriOpener for http/https schemes
• canOpenExternalUri() returns priority 2 for localhost URLs (Plannotator runs locally on dynamic ports)
• openExternalUri() routes to existing panel manager
• Type casting handles API missing from @types/vscode@1.85 (available since VSCode 1.54)
• Optional chaining provides graceful degradation

const windowWithOpener = vscode.window as typeof vscode.window & {
  registerExternalUriOpener?: (
    id: string,
    opener: { canOpenExternalUri(uri: Uri): number | undefined; openExternalUri(uri: Uri): void },
    metadata: { schemes: string[]; label: string }
  ) => Disposable;
};

windowWithOpener.registerExternalUriOpener?.(
  "plannotator-webview.opener",
  {
    canOpenExternalUri: (uri) => {
      const urlString = uri.toString();
      if (
        urlString.startsWith("http://localhost:") ||
        urlString.startsWith("https://localhost:") ||
        urlString.startsWith("http://127.0.0.1:") ||
        urlString.startsWith("https://127.0.0.1:")
      ) {
        return 2;
      }
      return undefined;
    },
    openExternalUri: (uri) => openInPanel(uri.toString())
  },
  { schemes: ["http", "https"], label: "Open Plannotator in VS Code" }
);

URL pattern matching rationale

• Matches localhost URLs specifically: Plannotator runs on localhost with dynamic ports (localhost:3000, localhost:8080, etc.)
• Matches both localhost and 127.0.0.1 hostnames
• Real Plannotator URLs don't contain "plannotator" in the path - they're just localhost:PORT URLs

Mock types (mocks/vscode.ts)

• Added ExternalUriOpener and ExternalUriOpenerMetadata interfaces
• Added registerExternalUriOpener to window mock
• Added Uri.toString() for URI handling in tests

Test coverage (src/extension.test.ts)

• Registration verification
• Priority 2 returned for http://localhost:3000/ and http://127.0.0.1:8080/review
• Undefined returned for http://example.com (pass-through)

Architecture

Both modes now supported:

1. Terminal mode (existing): PLANNOTATOR_BROWSER env var → router script → IPC server → webview
2. Extension mode (new): vscode.env.openExternal() → external URI opener (matches localhost URLs) → webview

Cookie proxy and panel management shared across both paths.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Ensure extension works with Claude Code VSCode extension, not just terminal</issue_title>
<issue_description>## Summary

The extension should work seamlessly when Claude Code is used as a VSCode extension, not only when invoked from the terminal.

Problem

Currently, the extension may only be tested/working when Claude Code is run from the terminal. Users who use the Claude Code VSCode extension integration need the same functionality available within their IDE workflow.

Expected Behavior

• Extension features should be fully functional when Claude Code is running as a VSCode extension
• All hooks, commands, and interactions should work identically whether Claude Code is launched from the terminal or within VSCode

Acceptance Criteria

• Verify extension activates correctly when Claude Code runs inside VSCode
• Ensure all hook integrations work in the VSCode extension context
• Test plan annotation workflows end-to-end in VSCode extension mode</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Ensure extension works with Claude Code VSCode extension, not just terminal #1

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[7tg]

@copilot url is just localhost there is not plannator

[Copilot]

Fixed in 863de5b. Changed URL matching from checking for "plannotator" substring to matching localhost URLs specifically:

• http://localhost:* and https://localhost:*
• http://127.0.0.1:* and https://127.0.0.1:*

This correctly matches actual Plannotator URLs which run on localhost with dynamic ports.