Launch 1M-capable Claude models with the [1m] window suffix#8
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Claude Code only switches its context meter and auto-compaction to the 1M window (and sends the context-1m beta) when the session model id carries the [1m] suffix. The selector and config.json advertise bare ids (claude-opus-4-8), so the launchers started Claude Code on a 200k window even for Opus 4.8 / Sonnet 4.6, which serve 1M natively -- the /context meter filled ~5x too fast and pinned at 100%, and auto-compaction was keyed to the wrong limit. Append [1m] to 1M-capable Claude base ids in both the POSIX (bin/ultracode) and Windows (Start-UltraCode.ps1) launchers, for the selector pick and the default settings model. Scoped so Haiku 4.5, claude-auto, and non-Claude routes (Gemini/GPT/Composer) are never suffixed. Configurable via UC_FORCE_1M (set 0 to disable) and UC_1M_MODELS (override the capable set). Symptom and toggles documented in docs/TROUBLESHOOTING.md. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Companion to #8. That PR makes the launchers append a "[1m]" suffix to 1M-capable Claude model ids so Claude Code sizes its context meter (and auto-compaction) to the 1M window. The suffix is a client-side convention -- the 1M window itself is carried by the context-1m beta header -- not an Anthropic model id. The proxy looks up routes (and orchestrator/worker picks) by exact id, so once a pick carries "[1m]" a configured route like "claude-opus" no longer matches "claude-opus[1m]" and routing falls through / breaks. This strips a trailing "[1m]" from the request model id up front, so "<id>[1m]" behaves exactly like "<id>" everywhere downstream. The 1M window is unaffected (the beta header is left untouched), and the strip is universal so stock-traffic remap and the Auto Router stay consistent too. Depends on #8: with #8 not merged nothing emits the suffix, so this is a no-op on its own and only earns its keep once #8 lands. Includes a unit test. Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
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Problem
Picking Opus 4.8 (or Sonnet 4.6) through the launcher, the
/contextmeterfills ~5× faster than expected and pins at 100%, and auto-compaction is keyed to
the wrong limit.
/contextshows the window as… / 200k, not/ 1M:Root cause
Claude Code only switches its context meter and auto-compaction to the 1M
window (and sends the
context-1mbeta) when the session's model id carries the[1m]suffix (e.g.claude-opus-4-8[1m]). The selector andconfig.jsonadvertise bare ids (
claude-opus-4-8), and the launchers pass those straightto
claude --model, so the client defaults to the 200k window — even thoughOpus 4.8 / 4.7 / 4.6 and Sonnet 4.6 serve 1M natively on the Anthropic API.
Nothing is lost upstream; the window is just mis-sized client-side. Verified that
claude --model 'claude-opus-4-8[1m]'is accepted and, after this change,/contextreads/ 1M.Fix
Both launchers now append
[1m]to 1M-capable Claude base ids before launch, forthe selector pick and the default settings model:
bin/ultracode—uc_add_1mhelperwindows/Start-UltraCode.ps1—Add-Uc1mfunctionScoped so Haiku 4.5,
claude-auto, and non-Claude routes(Gemini / GPT / Composer) are never suffixed.
Config:
UC_FORCE_1M=0— disable (back to bare ids)UC_1M_MODELS— comma-separated override of the capable set(default
claude-opus-4-8,claude-opus-4-7,claude-opus-4-6,claude-sonnet-4-6)Testing
bash -n bin/ultracodeclean;uc_add_1munit-tested across opus/sonnet (→suffixed), haiku/auto/gemini/already-suffixed/empty (→ unchanged), and
UC_FORCE_1M=0(→ disabled).windows/Start-UltraCode.ps1reviewed (${ModelId}[1m]interpolation; nopwshavailable in the dev env to run it)./contextnow shows/ 1M.Note
If an Anthropic-passthrough deployment can fall back to a backend capped at 200k,
a conversation that grows past 200k may then fail there — the new
TROUBLESHOOTING entry calls this out.
🤖 Generated with Claude Code