github-copilot: add 1M-context (`-1m`) Claude model variants

Summary

On 2026-06-04 GitHub announced that Copilot now supports 1M-token context windows and configurable reasoning levels across VS Code, Copilot CLI, and the GitHub Copilot app, "expanding to more surfaces soon":

📣 https://github.blog/changelog/2026-06-04-larger-context-windows-and-configurable-reasoning-levels-for-github-copilot/

Copilot exposes these capabilities via separate model IDs on the /models CAPI endpoint — model IDs with a -1m suffix, distinct entries from the 200k-context base models. The github-copilot provider on models.dev currently lists only the 200k base variants. The 1M variants are missing.

This matters because third-party clients use models.dev as their catalog. For example, opencode's opencode models --refresh literally fetches models.dev/api.json, so users cannot select the 1M variants even though the Copilot API serves them.

Related issues

• #1292 (open) — requests adding claude-opus-4.6-1m. Pre-dates yesterday's announcement; the announcement now makes this much more pressing and broader in scope.
• #1946 (closed 2026-06-02) — established the canonical pattern for github-copilot: model entries override [limit] with CAPI-actual values instead of inheriting from the upstream base model. This issue extends that pattern by adding the missing 1M variants as separate model files.

Missing model variants

Cross-referenced against CAPI dumps cited in #1292 comments and public reverse-engineering writeups (openclaw/openclaw#72824):

CAPI model ID	Context	Output	Reasoning (effort)	Status
claude-opus-4.6-1m	1,000,000	64,000	low / medium / high	GA — exposed to OAuth tokens
claude-sonnet-4.6-1m	1,000,000	64,000	—	GA
claude-opus-4.7-1m-internal	1,000,000	64,000	low / medium / high / xhigh	The -internal suffix in the CAPI model ID strongly suggests this is still first-party-only (VS Code / Copilot CLI / Copilot app). Recommend holding until GitHub drops the suffix, OR adding with a preview = true / experimental marker.

Are there other token-count variants?

Checked the obvious size/capability suffixes (-128k, -32k, -500k, -long, -extended, -fast, -turbo, -vision) in:

• The official docs page at https://docs.github.com/en/copilot/reference/ai-models/supported-models
• Recent dumps of /models from public repositories
• The microsoft/vscode-copilot-chat model registry

Conclusion: as of 2026-06-05, only -1m size suffix variants exist on Copilot CAPI, and only on the three Claude models above. GPT-5.x and Gemini families currently have a single base entry on Copilot (per #1946 verified limits: gpt-5.5=400k, gemini-3.1-pro-preview=200k). No other context-size variants are exposed. Maintainers should re-verify periodically since the announcement explicitly says "expanding to more surfaces soon".

How to verify with a live CAPI dump

Same one-liner from #1946, filtered for size-suffix model IDs:

curl -s https://api.githubcopilot.com/models \
  -H "Authorization: Bearer <copilot-token>" \
  -H "Editor-Version: vscode/1.0" \
  -H "Copilot-Integration-Id: vscode-chat" \
| jq '.data[] | select(.id|test("-1m|-long|-extended|-fast|-turbo|-vision")) |
      {id, ctx: .capabilities.limits.max_context_window_tokens,
            prompt: .capabilities.limits.max_prompt_tokens,
            out: .capabilities.limits.max_output_tokens,
            effort: .capabilities.supports.reasoning_effort}'

Suggested file additions

Mirror the post-#1946 shape. New files under providers/github-copilot/models/:

claude-opus-4.6-1m.toml

base_model = "anthropic/claude-opus-4-6"

# Pricing TBD — Copilot billing for the 1M variant may follow Anthropic's
# "long context" 2x multiplier above 200k input tokens, or it may follow
# the standard Copilot premium-request multiplier. Please verify against
# https://docs.github.com/en/copilot/managing-copilot/managing-copilot-as-an-individual-subscriber/about-billing-for-github-copilot

[limit]
context = 1_000_000
input   = 800_000   # verify via CAPI max_prompt_tokens
output  = 64_000

claude-sonnet-4.6-1m.toml

base_model = "anthropic/claude-sonnet-4-6"

[limit]
context = 1_000_000
input   = 800_000   # verify via CAPI max_prompt_tokens
output  = 64_000

claude-opus-4.7-1m-internal.toml — hold until GA (CAPI ID still has -internal suffix), OR add with a preview flag.

Also flagged: configurable reasoning levels

The same June 4 announcement covers "configurable reasoning levels". The upstream providers/anthropic/models/claude-opus-4-7.toml already declares:

[[reasoning_options]]
type = "effort"
values = ["low", "medium", "high", "xhigh", "max"]

…but the github-copilot models inherit only [cost] / [limit] overrides and may not propagate reasoning_options correctly. Worth verifying whether downstream clients see the effort tiers when selecting a github-copilot/claude-opus-4.x model, or whether this needs an explicit declaration. Likely a separate issue if it turns out to be broken.

---

Filed by an opencode user who hit the 200k context limit on github-copilot/claude-opus-4.7 immediately after seeing yesterday's announcement. Happy to open a PR with the two GA files if a maintainer confirms the suggested shape (especially the pricing/billing piece).

Start with the existing providers/github-copilot/models/ entries and the pattern established by issue #1946. Verify the live CAPI limits with the provided curl and jq command, then add the two GA model files with confirmed context, input, output, and pricing metadata. Treat claude-opus-4.7-1m-internal and reasoning options separately unless the maintainer confirms otherwise.