fix(opencode): add model aliases for GitHub Copilot model names

[mkusaka]

Summary

• map GitHub Copilot model names (dot notation) to LiteLLM pricing IDs
• ensure cost calculations resolve for Copilot logs where cost is 0
• keep existing behavior for other providers unchanged

Context

• OpenCode fetches model definitions from models.dev: https://github.com/anomalyco/opencode/blob/dev/packages/opencode/src/provider/models.ts#L88
• GitHub Copilot model names sourced from https://models.dev/api.json

Before/After

• Ran locally to validate the output: 2026-01-15 ran with OpenCode zen, 2026-01-16+ ran with GitHub Copilot subscription using Opus 4.5

Before

📊 OpenCode Token Usage Report - Daily

┌──────────┬─────────────────────────────────────────────────┬──────────┬──────────┬───────────┬──────────┬───────────┬──────────┐
│ Date     │ Models                                          │    Input │   Output │     Cache │    Cache │     Total │     Cost │
│          │                                                 │          │          │    Create │     Read │    Tokens │    (USD) │
├──────────┼─────────────────────────────────────────────────┼──────────┼──────────┼───────────┼──────────┼───────────┼──────────┤
│ 2026     │ - big-pickle                                    │   14,733 │       18 │         0 │      448 │    15,199 │    $0.00 │
│ 01-10    │                                                 │          │          │           │          │           │          │
├──────────┼─────────────────────────────────────────────────┼──────────┼──────────┼───────────┼──────────┼───────────┼──────────┤
│ 2026     │ - gpt-5.1-codex-max                             │  573,996 │   60,889 │    56,491 │ 3,780,2… │ 4,471,581 │    $2.30 │
│ 01-14    │ - sonnet-4-5                                    │          │          │           │          │           │          │
├──────────┼─────────────────────────────────────────────────┼──────────┼──────────┼───────────┼──────────┼───────────┼──────────┤
│ 2026     │ - claude-opus-4.5                               │  667,177 │  133,670 │   947,302 │ 23,721,… │ 25,469,9… │   $17.80 │
│ 01-15    │ - claude-sonnet-4.5                             │          │          │           │          │           │          │
│          │ - gpt-5.1-codex-max                             │          │          │           │          │           │          │
│          │ - opus-4-5                                      │          │          │           │          │           │          │
├──────────┼─────────────────────────────────────────────────┼──────────┼──────────┼───────────┼──────────┼───────────┼──────────┤
│ 2026     │ - claude-opus-4.5                               │ 2,294,1… │  189,483 │         0 │ 27,108,… │ 29,591,6… │    $0.00 │
│ 01-16    │                                                 │          │          │           │          │           │          │
├──────────┼─────────────────────────────────────────────────┼──────────┼──────────┼───────────┼──────────┼───────────┼──────────┤
│ 2026     │ - claude-opus-4.5                               │ 7,607,0… │  659,903 │         0 │ 180,860… │ 189,127,… │   $40.67 │
│ 01-17    │ - gpt-5.2-codex                                 │          │          │           │          │           │          │
├──────────┼─────────────────────────────────────────────────┼──────────┼──────────┼───────────┼──────────┼───────────┼──────────┤
│ Total    │                                                 │ 11,157,… │ 1,043,9… │ 1,003,793 │ 235,470… │ 248,675,… │   $60.78 │
└──────────┴─────────────────────────────────────────────────┴──────────┴──────────┴───────────┴──────────┴───────────┴──────────┘

After

📊 OpenCode Token Usage Report - Daily

┌──────────┬─────────────────────────────────────────────────┬──────────┬──────────┬───────────┬──────────┬───────────┬──────────┐
│ Date     │ Models                                          │    Input │   Output │     Cache │    Cache │     Total │     Cost │
│          │                                                 │          │          │    Create │     Read │    Tokens │    (USD) │
├──────────┼─────────────────────────────────────────────────┼──────────┼──────────┼───────────┼──────────┼───────────┼──────────┤
│ 2026     │ - big-pickle                                    │   14,733 │       18 │         0 │      448 │    15,199 │    $0.00 │
│ 01-10    │                                                 │          │          │           │          │           │          │
├──────────┼─────────────────────────────────────────────────┼──────────┼──────────┼───────────┼──────────┼───────────┼──────────┤
│ 2026     │ - gpt-5.1-codex-max                             │  573,996 │   60,889 │    56,491 │ 3,780,2… │ 4,471,581 │    $2.30 │
│ 01-14    │ - sonnet-4-5                                    │          │          │           │          │           │          │
├──────────┼─────────────────────────────────────────────────┼──────────┼──────────┼───────────┼──────────┼───────────┼──────────┤
│ 2026     │ - claude-opus-4.5                               │  667,177 │  133,670 │   947,302 │ 23,721,… │ 25,469,9… │   $20.76 │
│ 01-15    │ - claude-sonnet-4.5                             │          │          │           │          │           │          │
│          │ - gpt-5.1-codex-max                             │          │          │           │          │           │          │
│          │ - opus-4-5                                      │          │          │           │          │           │          │
├──────────┼─────────────────────────────────────────────────┼──────────┼──────────┼───────────┼──────────┼───────────┼──────────┤
│ 2026     │ - claude-opus-4.5                               │ 2,294,1… │  189,483 │         0 │ 27,108,… │ 29,591,6… │   $29.76 │
│ 01-16    │                                                 │          │          │           │          │           │          │
├──────────┼─────────────────────────────────────────────────┼──────────┼──────────┼───────────┼──────────┼───────────┼──────────┤
│ 2026     │ - claude-opus-4.5                               │ 7,607,0… │  659,903 │         0 │ 180,860… │ 189,127,… │   $75.86 │
│ 01-17    │ - gpt-5.2-codex                                 │          │          │           │          │           │          │
├──────────┼─────────────────────────────────────────────────┼──────────┼──────────┼───────────┼──────────┼───────────┼──────────┤
│ Total    │                                                 │ 11,157,… │ 1,043,9… │ 1,003,793 │ 235,470… │ 248,675,… │  $128.68 │
└──────────┴─────────────────────────────────────────────────┴──────────┴──────────┴───────────┴──────────┴───────────┴──────────┘

Closes

• Closes Add alias for github copilot model names #802

Summary by CodeRabbit

• New Features
  • Expanded AI model support for cost calculations, now including Claude 4.5, 4.x, 3.x Sonnet variants, Grok models, OpenCode high-tier variants, and Gemini 3 Pro.
  • Enhanced model name resolution system to accurately translate between naming conventions for consistent pricing lookups.

_{✏️ Tip: You can customize this high-level summary in your review settings.}

[coderabbitai]

📝 Walkthrough

Walkthrough

Added a MODEL_ALIASES map to cost-utils.ts that translates GitHub Copilot's dot-notation model names (e.g., claude.4.5) to LiteLLM-compatible hyphen-notation (e.g., claude-sonnet-4.5) for accurate pricing lookups across Claude, Grok, OpenCode, and Gemini variants.

Changes

Cohort / File(s)	Summary
Model Alias Mapping apps/opencode/src/cost-utils.ts	Added 20 lines introducing MODEL_ALIASES constant with mappings for Claude 4.5/4.x variants, Claude 3.x sonnet variants, Grok models with provider prefixes, OpenCode high-tier variants, and Gemini 3 Pro high; consumed by resolveModelName() and calculateCostForEntry() for cost calculation

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~5 minutes

Possibly related PRs

• PR #743: Expands isClaudeModel to detect anthropic.claude-/* prefixes, complementing this PR's alias-based normalization for Claude model name variations.

Suggested reviewers

• ryoppippi

Poem

🐰 A map of names, dot-dots to dashes,
Aliases spark like quick lightning flashes!
From Claude to Grok, the prices align,
No more zero costs—now pricing feels fine! ✨

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'fix(opencode): add model aliases for GitHub Copilot model names' clearly and specifically describes the main change—adding model aliases for GitHub Copilot naming conventions to resolve pricing lookups.
Linked Issues check	✅ Passed	The pull request implements the primary objective from issue #802: adding aliases to map GitHub Copilot model names (dot notation, provider prefixes, shorthand) to LiteLLM pricing identifiers to resolve missing cost calculations.
Out of Scope Changes check	✅ Passed	All changes are strictly focused on adding the MODEL_ALIASES map in cost-utils.ts to resolve GitHub Copilot model naming issues; no unrelated code modifications are present.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing touches

• 📝 Generate docstrings

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

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