Thinking

Some models emit reasoning ("thinking") tokens before their actual answer. The thinking/ package isolates that content so the daemon can return it as a separate field and the CLI can render it differently.

Purpose

Keep reasoning content visible without confusing it with the model's final answer. The CLI dims thinking output; API consumers read it from a separate field; tooling can choose to discard it entirely.

Key abstractions

Symbol	Location	Purpose
Stream parser	thinking/	Detects the start and end of a thinking block in a token stream and emits typed events (thinking-start, thinking-delta, thinking-end).
Capability thinking	types/model/capabilities.go	Models advertise this when their template uses thinking blocks.

How it works

graph LR
    Stream[runner token stream] --> Parser[thinking parser]
    Parser -->|inside thinking block| ThinkingDelta[thinking content]
    Parser -->|outside| ContentDelta[regular content]

The parser uses model-specific delimiters (e.g., <think>...</think> for some models, harmony channels for GPT-OSS-style models). Which delimiters apply is decided by the parser registered for the model family in model/parsers/.

API surface

• Per-request think flag (enable/disable thinking output). Recently extended to accept "max" as a value (api: accept "max" as a think value (#15787)).
• Per-response thinking field on ChatResponse (api/types.go).
• OpenAI compat: responses endpoint maps reasoning_effort to the think flag (openai: map responses reasoning effort to think (#15789)).

Integration points

• The daemon checks model.CheckCapabilities(CapabilityThinking) before handling think=true.
• The CLI's ensureThinkingSupport (cmd/cmd.go) warns when the user runs a model that doesn't support thinking.
• The OpenAI/Anthropic compat layers translate thinking to/from the right field name (reasoning_content for Anthropic, reasoning_effort for OpenAI Responses).

Entry points for modification

• New delimiter style → add a model-family parser in model/parsers/<family>/.
• New API surface (e.g., a different think value) → extend api/types.go and the corresponding middleware translator.

Key source files

File	Purpose
thinking/	Parser for thinking blocks.
types/model/capabilities.go	CapabilityThinking.
cmd/cmd.go	ensureThinkingSupport warning.
middleware/openai.go, middleware/anthropic.go	Compat translation.