feat(models): add Claude Sonnet 5.5

[Gigioxx]

What Changed

Claude Code 2.1.284 shipped today with Claude Sonnet 5.5 (claude-sonnet-5-5), and T3 Code doesn't list it yet. This adds it to the model manifest (JSON only), following #13094 (Opus 5.5):

• New claude-sonnet-5-5 entry, current, with the new badge and minVersion: 2.1.284. It sits next to Sonnet 5 in the list.
• New sonnet-5-5 profile. It has the same options as sonnet-5 (effort low to max plus ultrathink, 200k/1M context), but the default effort is medium instead of high.
• Sonnet 5 moves to Legacy models (still selectable), so the picker shows one current Sonnet. It is also replaced by Sonnet 5.5 in currentModels.claudeAgent, like Opus 5 was in 17e3477.
• Aliases are unchanged. sonnet still points to Sonnet 5, so Claude Code below 2.1.284 keeps working.
• updatedAt is bumped so existing installs pick this up through the remote manifest.

Why

Everything in the entry was checked against the 2.1.284 binary:

• The model catalog bundled in 2.1.284 lists claude-sonnet-5-5 with max_effort, xhigh_effort, native 1M context, no fast_mode, and default_effort: "medium". The medium default is the only difference from Sonnet 5, so it needs its own profile.
• claude -p --model 'claude-sonnet-5-5[1m]' --effort max and --model claude-sonnet-5-5 --effort low both work on 2.1.284. On 2.1.283 the CLI reports claude-code:unrecognized_model and falls back to a 200k window, so that's where the minVersion comes from.

UI Changes

With Claude Code 2.1.284, Sonnet 5.5 shows up as NEW in the picker, Sonnet 5 is under Legacy models, the default is Medium · 200k, and a turn runs on claude-sonnet-5-5:

Tests: vp test run on ModelManifest.test.ts, ClaudeModelCatalog.test.ts and ClaudeAdapter.test.ts pass, and vp fmt --check is clean.

Checklist

• This PR is small and focused
• I explained what changed and why
• I included before/after screenshots for any UI changes
• I included a video for animation/interaction changes (n/a)

Changes made by Claude Opus 5.5 in Claude Code, running in T3 Code.

Summary by CodeRabbit

• New Features
  • Added Claude Sonnet 5.5 as a selectable model with a “New” badge, reasoning options, and a 200k context window selected by default.
  • Added an option for a 1M context window.
• Updates
  • Claude Sonnet 5 is now listed as a legacy model.
  • Claude Sonnet 5.5 requires Claude Code version 2.1.284 or later.

[macroscopeapp]

Approvability

Verdict: Not approved

Macroscope's review found this PR not approvable — This change adds a user-facing Claude model and wires its effort, context-window, version gating, and [1m] model-ID behavior into production selection. Existing defaults and aliases remain intact, but the new model-specific runtime defaults and adapter behavior warrant human review.

^{You can add or adjust custom eligibility rules. Learn more.}

[coderabbitai]

Navigate logical layers of code changes, visualize relationships, and explore their blast radius.

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository: pingdotgg/t3code/.coderabbit.yaml

Review profile: CHILL

Plan: Advanced

Run ID: 968866a7-2d6b-4c40-95cf-152d5f7bb86e

📥 Commits

Reviewing files that changed from the base of the PR and between 28e12cb and 548fcd4.

📒 Files selected for processing (1)

• apps/server/src/provider/model-manifest.json

Included review availability: This review used your included allowance. Your plan provides up to 10 included reviews per hour; 7 remain after this review.

---

📝 Walkthrough

Walkthrough

The provider manifest adds Claude Sonnet 5.5 as a current model. It defines reasoning and context-window options, Claude Code adapter mappings, and a minimum Claude Code version. Claude Sonnet 5 becomes legacy.

Changes

Claude Sonnet 5.5

Layer / File(s)	Summary
Sonnet 5.5 profile and registration apps/server/src/provider/model-manifest.json	Adds the sonnet-5-5 profile with reasoning and context-window options, including Claude Code adapter mappings. Registers Claude Sonnet 5.5 as current with a new badge and minimum Claude Code version 2.1.284. Marks Claude Sonnet 5 as legacy and updates the manifest timestamp.

Priority: ⬇️ Low

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Feature

Suggested reviewers: juliusmarminge

Merge Risk: ⚪ Minimal · up to 548fc

No merge-blocking defect is established. The owner should clarify whether moving Sonnet 5 to legacy is intended, since the PR description and commit message conflict.

Architecture Summary

Architecture risk: 🔵 Low · up to 548fc

The change affects 1 system.

Changed systems: apps/server

Architecture concerns
No architecture-level concerns identified.

Review details

Systems and components

• observed — apps/server (service) was modified; 1 changed file maps to changed impact.

Before / after behavior

• observed — Modified behavior in apps/server/src/provider/model-manifest.json: Updates the manifest’s updatedAt value from 2026-09-24T18:40:00Z to 2026-09-28T19:22:00Z.
• observed — Modified behavior in apps/server/src/provider/model-manifest.json: Replaces claude-sonnet-5 with claude-sonnet-5-5 in Claude Agent’s current model list.
• observed — Modified behavior in apps/server/src/provider/model-manifest.json: Adds the sonnet-5-5 profile with selectable reasoning effort (medium by default) and context window (200k by default), including the ultrathink prompt-injected value. Its Claude Code adapter maps ultrathink to no effort value, adds the [1m] suffix for 1M context, and maps 200k and 1M to their token counts.
• observed — Modified behavior in apps/server/src/provider/model-manifest.json: Adds Claude Sonnet 5.5 as a current model with a new badge, the sonnet-5-5 profile, and Claude Code minimum version 2.1.284. Changes Claude Sonnet 5’s status from current to legacy.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title clearly and concisely identifies the main change: adding Claude Sonnet 5.5 support.
Description check	✅ Passed	The description covers what changed, why it changed, UI impact, validation results, and the checklist. It is detailed and relevant. The unchecked video item is acceptable because the change does not i…

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create a new PR

---

_{Comment @coderabbitai help to get the list of available commands.}

[juliusmarminge]

Superseded by #14152, which already merged Claude Sonnet 5.5 into the model manifest on main. Closing this duplicate so we do not land a second conflicting catalog change.