fix: expose GPT-5.6 Codex models

[neubig]

I tested this through the agent canvas and it works.

• A human has tested these changes.

---

Why

The TypeScript client's generated ACP provider registry still pinned the retired Codex ACP adapter, so Agent Canvas could not offer the current GPT-5.6 model family before a session started.

Summary

• mirror the SDK's @agentclientprotocol/codex-acp@1.1.2 command and agent-full-access mode
• expose GPT-5.6, Sol, Terra, and Luna in the generated Codex model registry
• cover the adapter contract and model IDs in the registry test
• validate registry changes against the immutable head SHA of a companion SDK PR linked in this description

Issue Number

N/A

How to Test

• npm run lint (0 errors; 17 pre-existing warnings)
• npm run build
• npm run test:coverage (284 passed)
• npm run format:check
• uv run python /home/gneubig/work/typescript-client/scripts/check-acp-drift.py from the companion SDK checkout (registry matches all 3 providers)
• installed the companion SDK PR through the same Git URL resolved by CI and reran scripts/check-acp-drift.py (passed)

Video/Screenshots

Not applicable; this PR mirrors generated provider metadata. End-to-end GPT-5.6 QA is documented in the companion SDK PR.

Type

• Bug fix
• Feature
• Refactor
• Breaking change
• Docs / chore

Notes

Companion SDK PR: OpenHands/software-agent-sdk#4056

Closes OpenHands/software-agent-sdk#4750

[github-actions]

Endpoint audit

❌ 6 off-contract call(s) — not on the agent-server · classifiers: cloud

Category	Count
❌ Off-contract (not on agent-server)	6
⛔ no known backend	5
↗️ served by cloud	1
➕ Missing API (agent-server has, client lacks)	9
agent-server endpoints	119
client endpoints	114

❌ Not on agent-server (gated, 6)

⛔ (no known backend) — served by no backend we can see (5)

• DELETE /api/meta-profiles/{}
• GET /api/meta-profiles
• GET /api/meta-profiles/{}
• POST /api/meta-profiles/{}
• POST /api/meta-profiles/{}/activate

↗️ served by cloud (1)

• GET /api/shared-events/search

➕ Missing API — agent-server exposes it, client does not implement (9)

• GET /
• GET /api/conversations
• GET /api/conversations/{}/events
• GET /api/conversations/{}/workspace
• GET /api/conversations/{}/workspace/{}
• GET /api/file/archive
• GET /api/init
• POST /api/conversations/{}/load_plugin
• POST /api/init

[simonrosenberg]

should we retire gpt-5.5 models? (that's also a problem we have a cloud: we propose old non-frontier models, good for not breaking anything during migrations but at some point they should go away)

[VascoSch92]

is this correct? Just asking

[neubig]

Yes, this is useful to test CI when typescript-client depends on an unreleased version of openhands-sdk.

[neubig]

@simonrosenberg I don't think we need to retire old models immediately.

[openhands-release-bot]

🚀 Released in v1.33.0.