Use config alias/name instead of API model ID in system prompt environment block #36164

Description

When users ask “What model are you using?”, the assistant answers with the internal API ID (e.g. claude-sonnet-4-20250514) instead of the config alias (my-sonnet) or display name (My Sonnet Alias).

This makes alias configuration inconsistent: users configure friendly names in config, but the model is explicitly told to identify itself by the raw provider ID.

OpenCode supports config-based model aliases:

{
"provider": {
"anthropic": {
"models": {
"my-sonnet": {
"id": "claude-sonnet-4-20250514",
"name": "My Sonnet Alias"
}
}
}
},
"model": "anthropic/my-sonnet"
}

Session metadata and the TUI already use the alias and display name. However, the system prompt in SystemPrompt.environment() always injects the API model ID:

// packages/opencode/src/session/system.ts:65
You are powered by the model named ${model.api.id}. The exact model ID is ${model.providerID}/${model.api.id}

Plugins

No response

OpenCode version

1.17.10

Steps to reproduce

1. Add a model alias in opencode.json (see above).
2. Start a session with anthropic/my-sonnet.
3. Ask: “What model are you currently using?”
   Expected: My Sonnet Alias or anthropic/my-sonnet
   Actual: claude-sonnet-4-20250514 or anthropic/claude-sonnet-4-20250514

Screenshot and/or share link

No response

Operating System

windows11

Terminal

No response