Function sidecar_search 

pub fn sidecar_search(
    log: &ReductionLog,
    minted_view: &[ChatMessage],
    recorded: Option<&[ChatMessage]>,
    query: &str,
) -> Result<SidecarSearchResult>

Resolve the sidecar_search(query) agent intrinsic (SPEC.md TR-1 dev/04): substring/regex search over content CURRENTLY reduced out of the view — every Reduction in log, restricted to its hidden_span so a still-visible portion (e.g. ToolOutputTruncated’s kept prefix) is never matched. “The same string visible in the live view is not double-reported” is upheld entirely from the log’s own records — this still never inspects the live view: for most kinds the hidden span is a pure function of the reduction itself, and for ReductionKind::DuplicateOutput (TR-2, whose content is byte-identical to a canonical instance that is usually still fully visible) visibility is decided by whether any OTHER log record reduces the canonical’s address — no per-message record there and no enclosing TurnsCleared range means the canonical is fully visible, so the duplicate’s content is not hidden and search skips it (hidden_span returns None). See the module doc comment for the minted_view/recorded two-source contract.

An empty (or all-whitespace) query is an error, not a match-everything wildcard: the empty pattern compiles as a regex that matches at every position, which is never what a caller meant and used to make the result size explode.

query is tried as a case-insensitive regex first; a query that fails to compile as one (e.g. literal text with an unbalanced [/(, common in file paths or code) falls back to a plain case-insensitive substring search, so both “search for this exact snippet” and “search with a pattern” work without the caller ever needing to escape anything.