The speed=fast allowlist still gates on Opus 4.6, but the fast-mode
matrix has changed twice since it was written (verified against the
live docs, platform.claude.com/docs/en/build-with-claude/fast-mode):
- Opus 4.8 and Opus 5 SUPPORT fast mode (research preview, Claude API
only — not Bedrock/Vertex/Foundry).
- Opus 4.6 LOST fast mode on 2026-06-29. The parameter does not error:
requests silently run at standard speed and bill standard rates
(usage.speed: 'standard'). Today's allowlist therefore shows 4.6
users a fast toggle that does nothing, while denying it to the two
models that actually support it.
- Opus 4.7 never had it and hard-400s (unchanged).
- Dedicated '…-fast' model ids (OpenRouter's claude-opus-4.8-fast)
select fast inference via the model field and are explicitly
excluded from the param gate.
Both gates move in lock-step as before: the adapter param gate
(agent.anthropic_adapter._supports_fast_mode) and the CLI toggle gate
(hermes_cli.models._is_anthropic_fast_model). Docstrings now record
the history in both directions so the next matrix change has context.
## How to test
scripts/run_tests.sh tests/agent/test_anthropic_adapter.py tests/cli/test_fast_command.py -- -q
113 tests pass. The updated predicate/matrix tests fail against the
previous allowlist (verified by stashing the source changes). Tested
on Linux (aarch64).
Aldo
6ff9426d22