Effort strings require adaptive-capable models
-
Every string effort value on Anthropic is sent as adaptive thinking (output_config.effort), which only newer Claude models (Opus 4.6+) accept. For older models like Sonnet 4.5, use an integer token budget instead. Conversely, models that only support adaptive thinking (Opus 4.6, 4.7, 4.8) automatically have token budgets coerced to adaptive (a warning is logged).
+
Every string effort value on Anthropic is sent as adaptive thinking (output_config.effort), which only newer Claude models (Opus 4.6+, Sonnet 4.6) accept. For older models like Sonnet 4.5, use an integer token budget instead. Conversely, models that only support adaptive thinking (Opus 4.6, 4.7, 4.8, Sonnet 4.6) automatically have token budgets coerced to adaptive (a warning is logged).
### Disabling thinking
@@ -332,7 +333,7 @@ models:
While running in the TUI, press **Shift+Tab** to cycle the thinking effort level for the current model without editing your YAML config:
-- The level steps through the model's supported range (model-specific), wrapping around — for example `none → minimal → low → medium → high → none` on OpenAI gpt-5/o-series, `none → minimal → low → medium → high → xhigh → none` on gpt-5.2+, `none → low → medium → high → max → none` on Anthropic Opus 4.6, and `none → low → medium → high → xhigh → none` on Anthropic Opus 4.7+. For older Anthropic models (e.g. Sonnet 4.5) that only accept token budgets, effort-string cycling has no effect — use an integer `thinking_budget` in your YAML config instead.
+- The level steps through the model's supported range (model-specific), wrapping around — for example `none → minimal → low → medium → high → none` on OpenAI gpt-5/o-series, `none → minimal → low → medium → high → xhigh → none` on gpt-5.2+, `none → low → medium → high → max → none` on Anthropic Opus 4.6 and Sonnet 4.6, and `none → low → medium → high → xhigh → max → none` on Anthropic Opus 4.7+, Fable 5, and Mythos 5. For older Anthropic models (e.g. Sonnet 4.5) that only accept token budgets, effort-string cycling has no effect — use an integer `thinking_budget` in your YAML config instead.
- The current level is shown in the sidebar next to the model name (e.g. `openai/gpt-5 • high`).
- This applies as a session override — it is **not** saved to the config file. The next session starts from the level defined in your YAML.
- For models that don't support reasoning, and for remote runtimes, Shift+Tab is a no-op and an informational message is displayed.
diff --git a/docs/providers/anthropic/index.md b/docs/providers/anthropic/index.md
index c018d1e14..df0575c6b 100644
--- a/docs/providers/anthropic/index.md
+++ b/docs/providers/anthropic/index.md
@@ -116,7 +116,7 @@ models:
thinking_budget: 16384 # must be < max_tokens
```
-**Adaptive / effort-based** (Claude Opus 4.6+ only — every string value is sent as adaptive thinking via `output_config.effort`):
+**Adaptive / effort-based** (Claude Opus 4.6+, Sonnet 4.6 — every string value is sent as adaptive thinking via `output_config.effort`):
```yaml
models:
@@ -131,7 +131,7 @@ models:
thinking_budget: high # low | medium | high | xhigh | max (same as adaptive/