[Bug]: Claude picker ignores availableModels and ANTHROPIC_DEFAULT_*_MODEL; picking Haiku on Bedrock silently runs Opus #24214

Before submitting

• I searched existing issues and did not find a duplicate.
• I included enough detail to reproduce or investigate the problem.

Area

apps/server

Steps to reproduce

1. Configure Claude Code for Amazon Bedrock in ~/.claude/settings.json, using the ANTHROPIC_DEFAULT_* env vars and an availableModels allowlist with Bedrock IDs:

   {
     "env": {
       "CLAUDE_CODE_USE_BEDROCK": "1",
       "AWS_REGION": "us-west-2",
       "ANTHROPIC_DEFAULT_OPUS_MODEL": "global.anthropic.claude-opus-5-5",
       "ANTHROPIC_DEFAULT_OPUS_MODEL_NAME": "Opus 5.5 via Bedrock Global (1M context)",
       "ANTHROPIC_DEFAULT_SONNET_MODEL": "global.anthropic.claude-sonnet-5-5[1m]",
       "ANTHROPIC_DEFAULT_SONNET_MODEL_NAME": "Sonnet 5.5 via Bedrock Global (1M context)",
       "ANTHROPIC_DEFAULT_HAIKU_MODEL": "global.anthropic.claude-haiku-5-5",
       "ANTHROPIC_DEFAULT_HAIKU_MODEL_NAME": "Haiku 5.5 via Bedrock Global"
     },
     "model": "opus",
     "availableModels": [
       "global.anthropic.claude-haiku-5-5",
       "global.anthropic.claude-sonnet-5-5",
       "global.anthropic.claude-opus-5-5"
     ]
   }

2. Add a Claude provider instance in T3 Code that uses ~/.claude (default config dir, no custom models).

3. In the model picker, select Claude Haiku 5.5 and send a prompt.

Expected behavior

The Claude picker reflects the Claude Code configuration, the same way /model does in the CLI:

• Rows map to the configured Bedrock IDs (ANTHROPIC_DEFAULT_{OPUS,SONNET,HAIKU}_MODEL), labeled with the *_MODEL_NAME / *_MODEL_DESCRIPTION values when set.
• Models not in availableModels are not offered.
• Selecting Haiku runs global.anthropic.claude-haiku-5-5.

Passing the alias (haiku, sonnet, opus) or the resolved Bedrock ID to Claude Code would also fix the routing. Both work in the CLI (see Evidence).

Actual behavior

The picker shows T3's bundled first-party catalog (claude-opus-5-5, claude-haiku-5-5, ...) and sends that slug to the SDK. Claude Code rejects it because it is not in availableModels, and silently falls back to the default model (Opus). The UI still shows Haiku. No error appears.

T3's provider event log shows the mismatch for every thread where a non-default model was picked:

query.open  options.model = "claude-haiku-5-5"            # sent by T3
system/init model         = "global.anthropic.claude-opus-5-5"  # what Claude Code actually runs

So users pay for Opus while the UI shows Haiku, and there is no way to get Sonnet or Haiku without extra T3-side config.

Same CLI (claude -p --model <x> --output-format json, modelUsage keys) with the settings above:

Adding claude-haiku-5-5 to availableModels doesn't help either: Claude Code then sends that raw ID to Bedrock and the request fails.

Related, but not duplicates: #23279 (custom modelPicker in settings, fixed) and #13875 (gateway model discovery, fixed). This report is about availableModels and the ANTHROPIC_DEFAULT_*_MODEL env vars, which T3 doesn't read today. From the discussion on #13875, reported models whose ID or alias matches a catalog entry are skipped, so the catalog slug always wins.

Impact

Major degradation or frequent failure

Version or commit

T3 Code (Beta) 0.1.2

Environment

macOS 26 (Darwin 25.6.0), Claude Code 2.1.309, Claude provider via Amazon Bedrock (CLAUDE_CODE_USE_BEDROCK=1, global.* inference profiles)

Workaround

Add the Bedrock IDs as customModels on the Claude provider instance in T3 and pick those rows instead of the built-in ones. This duplicates config that already lives in ~/.claude/settings.json.