Add initial turns page to app-server thread resume

[shiny-code-bot]

Objective

Adapt the useful part of Codex CLI's app-server resume improvements without porting the whole upstream desktop API stack.

Finish Line

Every Code's v2 thread/resume response can optionally include the first page of thread turns so desktop or remote clients can hydrate a resumed thread without a second immediate read.

Current Status

State: Created from #216 Codex CLI app-server audit.
Next action: Wait until Every Code chooses to make v2 app-server thread lifecycle a real client surface, then design the exact response shape against code-rs/app-server-protocol and runtime handlers.
Blocked by: None.
Waiting for: Product decision on desktop/app-server client direction (#217/#37).
Last verified: 2026-05-30.

Scope

• Adapt the product value from OpenAI Codex commit 2a1158b8e2 (feat(app-server): include turns page on thread resume).
• Avoid blind modular protocol refactors or wholesale v2 API imports.
• Preserve current v1 app-server behavior unless the implementation deliberately wires v2 thread lifecycle.

Acceptance Criteria

• ThreadResumeResponse can return an optional initial turns page with stable pagination semantics.
• Runtime app-server handling, not only schema types, supports the response.
• Sensitive or payload-heavy history exposure is reviewed alongside Add initial turns page to app-server thread resume #226.
• App-server client/resume tests cover response shape and ordering.
• ./build-fast.sh passes cleanly.

Evidence

• Current Every Code protocol already declares v2 ThreadResumeParams, ThreadResumeResponse, ThreadListParams, ThreadReadParams, and related turn/history types.
• The current editable app-server mostly implements v1 conversations plus selected v2 config/account paths, so this is valuable only when v2 thread lifecycle becomes a product surface.

Relationships

• Parent audit: Audit Codex CLI app-server parity for Every Code #216.
• Remote/desktop direction: Investigate Codex desktop app remote control compatibility #217 and Evaluate upstream app-server remote-control support #37.

Validation

• Run ./build-fast.sh from repo root.
• Add focused protocol/runtime tests for resume hydration once implemented.