Consistent Tab IDs & Global Tag Targeting

[DJRHails]

• replace positional tab indices with tab IDs across tab commands and response payloads
• add global --tab <id> so page-scoped commands can target a tab directly
• scope --tab routing so commands restore the previous active tab when they temporarily target a different tab
• Fix the tab_list fallback which can be a bit confusing (especially when LLMs hallucinate a tab switch functionality).

Personally I'm not in love with the incrementing integer as the id; but it's a pretty significant refactor otherwise. I've still currently made one breaking change by renaming 'index' -> 'tabId' but that seems worth it for the clarity of code.

Motivation

Shared-browser CDP workflows break down when tabs are addressed by positional index because unrelated tab churn changes what a given index points to.

Example:

$ agent-browser tab list
  [0] App - https://app.example.com
  [1] Docs - https://docs.example.com
→ [2] Google - https://www.google.com/

# Another workflow closes a different tab
$ agent-browser tab close 1
✓ Tab 1 closed

$ agent-browser tab list
  [0] App - https://app.example.com
→ [1] Google - https://www.google.com/ (should be [2])

Or another page opens a popup/new tab:

$ agent-browser tab list
→ [0] App - https://app.example.com
     [1] Google - https://www.google.com/

# Another workflow opens a popup (you expect it at tab 11)
$ agent-browser tab list
  [0] App - https://app.example.com
  [1] Google - https://www.google.com/
  [2] Popup - https://accounts.example.com/

With tab IDs, existing tabs keep the same identifier even when other tabs are closed or popups appear, so agents can continue targeting the same tab across commands.

Testing

• pnpm exec vitest run src/browser.test.ts src/protocol.test.ts src/daemon.test.ts
• pnpm exec tsc --noEmit
• cargo test --manifest-path cli/Cargo.toml tab_
• cargo test --manifest-path cli/Cargo.toml parse_tab_flag
• cargo test --manifest-path cli/Cargo.toml clean_args_removes_tab_flag

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[DJRHails]

Hey @mvanhorn - just saw #883 - let me know what you think. Had this in a fork.

[mvanhorn]

Hey @DJRHails - the stable tab ID approach looks solid. My #883 uses positional indexes which is simpler but less robust. I'd defer to @ctate on which direction to go - happy to close mine if the ID-based approach is preferred.

[mvanhorn]

Interesting approach with persistent tab IDs - that's a cleaner foundation than positional indices. Happy to rebase #883 on top of yours if @ctate prefers your approach, or we can coordinate to merge the concepts.