Function parse_json_tool_call

server/src/server/tool_parser.cpp:343–383

Parse {"name": ..., "arguments": ...} or {"function": {"name": ..., "arguments": ...}}

    return r;
}

// Pattern 5: `call:<ns>?<verb>{` opener. The sentinel alternation in front
// rejects narrative usages like "I'll call:foo{x:1}" where `call:` is glued
// to a preceding word — whitespace, common punctuation, and open/close
// brackets are the realistic boundaries seen in the snapshot data. `\s`
// covers `\n` so a `call:` at the start of any line is matched without
// relying on std::regex multiline support (which is non-portable).
//
// Note that `}` is in the sentinel list — gemma frequently emits multiple
// invocations back-to-back: `call:a{x:1}call:b{y:2}`. Without `}` as a
// sentinel the second match would be missed.
//
// `_` is also in the sentinel list to handle a SentencePiece / chat-template
// artifact: post-bragi-channel-routing (commit 4b757d1) the gemma server
// occasionally emits raw tokens like `_call:get_country_info{...}` where
// the leading `_` is residual tokenizer serialization. Without `_` here
// the parser misses every such invocation — empirically confirmed against
// gemma-4-26b 2026-05-31 smoke test. Tradeoff: `my_call:foo{}` mid-
// identifier could match, but real model output doesn't emit `my_call:`
// strings (tool names come from the request's tool definitions).
static const std::regex & re_call_verb_open() {
    static std::regex r(R"((^|[\s,;:\(\[\{\}\)\]\>_])call:([A-Za-z0-9_.:\-]+)\s*\{)");
    return r;
}

// Find the index one past the `}` that matches `text[open] == '{'`.
// Respects nested {}/[] depth and skips over "..." / '...' / `...`
// string literals (with backslash escapes). Returns std::string::npos if
// no matching close is found.
static size_t balanced_braces_end(const std::string & text, size_t open) {
    int depth = 0;
    char in_str = 0;  // 0, or one of '"', '\'', '`'
    for (size_t i = open; i < text.size(); i++) {
        char c = text[i];
        if (in_str) {
            if (c == '\\' && i + 1 < text.size()) { i++; continue; }
            if (c == in_str) in_str = 0;
            continue;
        }
        if (c == '"' || c == '\'' || c == '`') { in_str = c; continue; }
        if (c == '{' || c == '[') {
            depth++;
        } else if (c == '}' || c == ']') {
            depth--;