Support multi-select pending user inputs

[juliusmarminge]

Summary

• Add multiSelect support to Codex user-input questions and carry it through server/web parsing.
• Update pending-user-input state to track multiple selected option labels, including toggle behavior and answer resolution.
• Adjust composer UI and keyboard handling so multi-select questions stay open until the user advances, while single-select questions keep auto-advance.
• Expand tests to cover multi-select answer building, progress derivation, adapter parsing, and browser interaction flows.

Testing

• bun fmt
• bun lint
• bun typecheck
• bun run test

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Note

Medium Risk
Changes user-input question/answer shape to support multi-select, including different answer types (string vs string[]) and updated UI selection behavior; regressions could affect responding to prompts or keyboard shortcuts in the chat composer.

Overview
Adds end-to-end multiSelect support for pending user-input questions: server adapters/session parsing now preserve a multiSelect flag, and the web client can submit multi-select answers as arrays.

Updates pending user-input state and UI to track multiple selected option labels with toggle semantics, disables auto-advance for multi-select questions (single-select still auto-advances), and tightens numeric shortcut handling to avoid firing while the composer/contenteditable is focused.

Expands unit and browser tests to cover multi-select parsing, selection toggling, progress/answer resolution, and submission payloads.

^{Reviewed by Cursor Bugbot for commit 0ab01a7. Bugbot is set up for automated code reviews on this repo. Configure here.}

Note

Add multi-select support to pending user input questions

• Adds a multiSelect flag to user input question types in both pendingUserInput.ts and session-logic.ts, parsed from the activity payload.
• Replaces selectedOptionLabel: string with selectedOptionLabels: string[] throughout the pending user input data model to support multiple selections uniformly.
• Introduces togglePendingUserInputOptionSelection to toggle option state; multi-select questions accumulate selections while single-select questions replace them.
• Multi-select questions no longer auto-advance after an option is chosen; number key shortcuts (1–9) are blocked when focus is inside editable fields.
• resolvePendingUserInputAnswer returns string[] for multi-select questions and string for single-select; buildPendingUserInputAnswers propagates arrays in the final answers map.
• Behavioral Change: answer state shape changes from a single string to an array; any code reading selectedOptionLabel directly will break.

^{Macroscope summarized 0ab01a7.}

[macroscopeapp]

Approvability

Verdict: Needs human review

This PR introduces a new multi-select capability for user input questions, changing data structures from single to array-based selection and adding new toggle behavior. While well-tested and self-contained, it represents new user-facing functionality with runtime behavior changes that warrants human review.

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