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Remove the Claude 200k/1M context window option; always run 1M #16904

Description

@juliusmarminge

Follow-up to #16903 and supersedes #8405.

The Claude Context Window option (200k / 1M) doesn't do what it says. Picking 200k sends the bare slug, but Claude Code runs these models at 1M anyway unless the process sets CLAUDE_CODE_DISABLE_1M_CONTEXT=1. So the 200k choice is a no-op, and T3 reports a 200k limit (contextWindowTokens) for a session that actually has 1M. Macroscope flagged the same mismatch on the new Haiku 5.5 profile in #16903.

We don't want a 200k mode. Remove the option and always run 1M.

Scope

  • apps/server/src/provider/model-manifest.json: drop the contextWindow descriptor, modelSuffixes.contextWindow and contextWindowTokens from every Claude profile that has them (fable-5, opus-5-5, opus-5, opus-4-6, sonnet-5, sonnet-4-6, haiku-5-5). Declare fixedContextWindowTokens: 1000000 instead, like opus-4-8 / opus-4-7 already do.
  • Send the 1M model id unconditionally where Claude Code still needs the [1m] suffix to get 1M (check per model; Sonnet 5 and Sonnet 4.6 currently default to 200k).
  • opus-4-5 and haiku-4-5 are 200k-only models; leave them without the option. Give them a fixed 200k if the context meter needs a number.
  • Threads with a saved contextWindow: "200k" selection should keep working: the option is ignored, not an error.
  • Check that web and mobile pickers don't hard-code the option.
  • Close [Bug]: Claude 200k context window selection is a no-op; sessions always run at 1M #8405 once this lands.

Activity

  1. added 3 commits that reference this issue on Oct 7, 2026
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  2. juliusmarminge commented on Oct 7, 2026

    @juliusmarminge
    MemberAuthor

    Scoped down in #16908: the 5-series drops the option and runs a fixed 1M. Opus 4.6 and Sonnet 4.6 keep the 200k/1M option, since there it really switches the window.

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