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generate

wcode_harness::title

Function generate 

Source 
pub async fn generate(
    stream_fn: &StreamFn,
    opts: &LlmOpts,
    ctx: &[AgentMessage],
) -> Result<String, String>
Expand description

Ask the model for a session title and return the sanitized result.

The single model call is shaped exactly like crate::compaction::summarize (crates/wcode-harness/src/compaction.rs:628): one stream_fn invocation with an EMPTY tool list, the [TITLE_PROMPT] as system, and one AgentMessage::user_text carrying both halves; then a fold of LlmStreamEvent::TextDelta → String until Done (or Error).

§Contract

  • Input. The first user text and the first assistant text in ctx, each clamped to [TITLE_INPUT_CHARS], rendered as USER:\n<…>\n\nASSISTANT:\n<…> in ONE user message — the two halves the test name generate_collects_text_and_sends_both_halves asserts on. ctx[0] is SKIPPED when it is a compaction summary (it starts with COMPACTION_SUMMARY_PREFIX); see Session::messages (crates/wcode-harness/src/session.rs:186-188) which prepends one on a resume. Half-missing is not an error: a request with only the user half (an assistant turn that produced no text) still gets asked.
  • Output. Ok(title) where title is the output of sanitize — never empty, never longer than TITLE_CLAMP chars.
  • Empty answer (no TextDelta at all, only Done, or deltas that sanitize rejects): Err("titler produced no text"). Mirrors summarize’s Err("summarizer produced no text") (compaction.rs:660-662).
  • Stream error (LlmStreamEvent::Error { message, .. }): Err(message) verbatim, first error wins, the fold stops. Mirrors compaction.rs:654.
  • No input at all (no user text and no assistant text): Err("no input to title from") WITHOUT a model call — a request that cannot help is not sent.
  • Does NOT promise: a retry of its own (it inherits the adapter’s retry/idle policy exactly as summarize does), a usage report (the caller does not bill it), a cancel path (v1: the call is bounded by the adapter’s idle backstop, and the auto-trigger waits for it — D1’s accepted cost), or that the model follows [TITLE_PROMPT] — that is sanitize’s job.
  • Never panics.