docs: describe the disabled-thinking fallback

README.md

@@ -175,7 +175,7 @@ max_context_tokens = 200000
 
 Per-provider **`timeout`** is passed to the HTTP session for chat/completions, Responses, and `GET /models`. A single number sets one timeout; `{ connect, read }` splits TCP/TLS setup vs idle wait between response bytes (SSE can run longer than `read` while chunks keep arriving). Tool/process timeouts (`run_argv`, PTY, policy confirm) are separate.
 
-**Thinking strength** (`reasoning_effort`) can be set on `[agent]`, on a provider, or on a single model: the most specific layer wins, per field, so a model may override only the effort or only the budget. `""` sends nothing and lets the provider apply its own default. Each API surface maps the value onto its own wire field — chat completions send `reasoning_effort`, Responses send `reasoning.effort`, and Anthropic has no effort level at all, so it sends `thinking` with the token budget that level maps onto (`minimal` 1024 … `xhigh`/`max` 32768; `none` disables thinking); a model that no longer takes a budget answers 400 and wants adaptive thinking instead (from Claude 4.7 on), so the request is retried once as `thinking.type = "adaptive"` with the level in `output_config.effort`, and that model is remembered for the session — `thinking_budget_tokens` has no adaptive equivalent and is then ignored. `max` is DeepSeek's own top level on chat completions and clamps to `xhigh` everywhere else. `thinking_budget_tokens` overrides that mapping; either way the request stays valid: the budget never drops below 1024, and when it would swallow the output limit `max_tokens` grows so the answer still has room. DeepSeek chat keeps `thinking.type = "enabled"` unless the effort is `none`.
+**Thinking strength** (`reasoning_effort`) can be set on `[agent]`, on a provider, or on a single model: the most specific layer wins, per field, so a model may override only the effort or only the budget. `""` sends nothing and lets the provider apply its own default. Each API surface maps the value onto its own wire field — chat completions send `reasoning_effort`, Responses send `reasoning.effort`, and Anthropic has no effort level at all, so it sends `thinking` with the token budget that level maps onto (`minimal` 1024 … `xhigh`/`max` 32768; `none` disables thinking); a thinking block the model refuses is retried once with the shape it takes — adaptive thinking with the level itself as `output_config.effort` (from Claude 4.7 on), or no block at all where thinking cannot be turned off — and the refusal is remembered for the session, so `thinking_budget_tokens` is ignored on such a model. `max` is DeepSeek's own top level on chat completions and clamps to `xhigh` everywhere else. `thinking_budget_tokens` overrides that mapping; either way the request stays valid: the budget never drops below 1024, and when it would swallow the output limit `max_tokens` grows so the answer still has room. DeepSeek chat keeps `thinking.type = "enabled"` unless the effort is `none`.
 
 ```toml
 [providers.deepseek]