Add GPT-6 Astra model inventory support

[Copilot]

gpt-6-astra is live in Copilot and OpenAI inventories but was absent from model aliases and pricing metadata. This adds it to flagship fallback selection and cost accounting.

• Alias inventory

  • Add gpt-6 provider patterns.
  • Include it in large and agent resolution chains.

• Pricing catalog

  • Add gpt-6-astra costs to GitHub Copilot and OpenAI catalogs.
  • Keep actions/setup/js/models.json synchronized with the CLI catalog.

• Regression coverage

  • Verify alias ordering and provider patterns.
  • Verify GPT-6 Astra input, output, and cache pricing lookup.

"gpt-6": ["copilot/gpt-6*", "openai/gpt-6*"]

• Fixes [model-inventory] Model alias inventory update - 2026-09-09 #59709

[Copilot]

🟡 Changes recommended

GPT-6 Astra long-context usage would be materially undercounted until tiered pricing is implemented and synchronized.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Pull request overview

Adds GPT-6 Astra alias resolution and pricing support across workflow and runtime catalogs.

Changes:

• Adds GPT-6 aliases and fallback ordering.
• Adds synchronized Copilot/OpenAI pricing metadata.
• Adds regression tests for alias and pricing lookup.

File summaries

File	Review
pkg/workflow/model_aliases_test.go	Tests GPT-6 alias patterns and ordering.
pkg/workflow/data/model_aliases.json	Adds GPT-6 aliases and fallbacks; API documentation must be updated to match.
pkg/cli/model_costs_test.go	Tests default GPT-6 Astra pricing lookup.
pkg/cli/data/models.json	Adds CLI pricing, but lacks the >272k-token tier and threshold-aware accounting. A patch changeset is also missing.
actions/setup/js/models.json	Mirrors action pricing, but lacks the >272k-token tier and corresponding threshold-aware calculation.

Review details

Suppressed comments (2)

pkg/cli/data/models.json:518

• This user-visible inventory update has no .changeset entry, so its GPT-6 alias and pricing support will be omitted from the generated release notes. Recent model-inventory updates consistently add a patch changeset (for example, .changeset/patch-model-inventory-2026-08-27.md:1-5, .changeset/patch-model-inventory-2026-08-16.md:1-5, and .changeset/patch-model-inventory-2026-07-27.md:1-5). Please add a 2026-09-09 patch changeset describing both the alias and catalog additions.

        "gpt-6-astra": {

pkg/workflow/data/model_aliases.json:42

• Adding GPT-6 to this public built-in chain leaves BuiltinModelAliases' documentation stale: pkg/workflow/model_aliases.go:119-139 still omits the gpt-6 vendor alias and documents large without this entry. Update that API comment with the data change so callers are not given an obsolete resolution order.

    "large": ["sonnet", "gpt-6", "gpt-5-pro", "gpt-5", "gemini-pro"],

• Files reviewed: 5/5 changed files
• Comments generated: 2
• Review effort level: Balanced

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[github-actions]

🎉 This pull request is included in a new release.

Release: v0.89.0