path: root/src/config.cpp

#include "config.h"

#include <cjson/cJSON.h>
#include <ctype.h>
#include <errno.h>
#include <getopt.h>
#include <limits>
#include <sys/stat.h>
#include <math.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "compact.h"
#include "dotagents.h"
#include "tools.h"

#define DEFAULT_COMPACT_THRESHOLD 0.75
#define DEFAULT_CLEAR_THRESHOLD 0.5
#define DEFAULT_MAX_RETRIES 3UL
#define DEFAULT_SKILL_INDEX_CAP 50UL
#define DEFAULT_SHELL_TIMEOUT_SECS 120UL
#define DEFAULT_MAX_OUTPUT_CHARS 16000UL
#define DEFAULT_MAX_FILE_BYTES 2000000UL

/* The default system preamble. The "Available tools" section is generated
 * from the tool registry (tools.c) so it can't drift from the actual
 * tool set. */
static const char *PREAMBLE_HEAD =
    "You are an agent operating inside a terminal. You accomplish tasks by "
    "calling tools.\n"
    "\n";
static const char *PREAMBLE_TAIL =
    "\n"
    "Guidelines:\n"
    "- Paths may be relative to the working directory or absolute.\n"
    "- Inspect before you modify: use read_file, or run_shell with ls / "
    "rg / grep, to understand existing state.\n"
    "- Prefer small, verifiable steps. After making changes, verify them "
    "(e.g. run the build or tests with run_shell).\n"
    "- Keep run_shell commands safe and scoped to the task; avoid "
    "destructive commands unless explicitly asked.\n"
    "- When a task is complete, stop calling tools and reply with a short "
    "summary of what you did.";

char *default_preamble(void) {
    xbuf b;
    xbuf_init(&b);
    xbuf_put(&b, PREAMBLE_HEAD);
    char *tools = tool_preamble_list();
    xbuf_put(&b, tools);
    free(tools);
    xbuf_put(&b, PREAMBLE_TAIL);
    char *out = xbuf_steal(&b);
    xbuf_free(&b);
    return out;
}

/* ------------------------------------------------------------------ */
/* Providers                                                           */
/* ------------------------------------------------------------------ */

provider_kind provider_parse(const char *raw, char **err) {
    xbuf l;
    xbuf_init(&l);
    for (const char *p = raw; *p; p++)
        xbuf_push(&l, (char)tolower((unsigned char)*p));
    l.data[l.len] = '\0';
    const char *s = l.data;
    if (strcmp(s, "openai") == 0 || strcmp(s, "openai-compatible") == 0 ||
        strcmp(s, "openai_compatible") == 0) {
        xbuf_free(&l);
        return PROV_OPENAI;
    }
    if (strcmp(s, "anthropic") == 0 || strcmp(s, "claude") == 0) {
        xbuf_free(&l);
        return PROV_ANTHROPIC;
    }
    if (strcmp(s, "ollama") == 0) {
        xbuf_free(&l);
        return PROV_OLLAMA;
    }
    xbuf b;
    xbuf_init(&b);
    xbuf_fmt(&b, "unknown provider `%s` (expected openai, anthropic, or "
                 "ollama)",
             raw);
    xbuf_free(&l);
    char *r = xbuf_steal(&b);
    if (err)
        *err = r;
    else
        free(r);
    return PROV_OPENAI;
}

const char *provider_name(provider_kind k) {
    switch (k) {
    case PROV_OPENAI:
        return "openai";
    case PROV_ANTHROPIC:
        return "anthropic";
    case PROV_OLLAMA:
        return "ollama";
    }
    return "openai";
}

static const char *provider_debug(provider_kind k) {
    switch (k) {
    case PROV_OPENAI:
        return "OpenAI";
    case PROV_ANTHROPIC:
        return "Anthropic";
    case PROV_OLLAMA:
        return "Ollama";
    }
    return "OpenAI";
}

const char *provider_default_model(provider_kind k) {
    switch (k) {
    case PROV_OPENAI:
        return "gpt-5.2";
    case PROV_ANTHROPIC:
        return "claude-sonnet-4-6";
    case PROV_OLLAMA:
        return "llama3.2";
    }
    return "gpt-5.2";
}

/* ------------------------------------------------------------------ */
/* CLI parsing                                                         */
/* ------------------------------------------------------------------ */

static void print_usage(FILE *f) {
    fprintf(
        f,
        "llsh %s\n"
        "llsh — a terminal LLM agent harness built on rig\n"
        "\n"
        "Usage: llsh [OPTIONS] [PROMPT]\n"
        "\n"
        "Arguments:\n"
        "  [PROMPT]  One-shot prompt. If omitted (and stdin is a TTY), "
        "launches the interactive REPL.\n"
        "\n"
        "Options:\n"
        "      --model <MODEL>  Model name, e.g. `gpt-5.2`, "
        "`claude-sonnet-4-6`, `llama3.2`; or a `.agents/models.json` "
        "preset name (which also brings that preset's "
        "provider/base_url/api_key). Overrides the preset's `model`; "
        "defaults per provider when unset\n"
        "      --provider <PROVIDER>  Model provider: `openai`, "
        "`anthropic`, or `ollama`. `openai` also works against any "
        "OpenAI-compatible endpoint via `--base-url`\n"
        "      --base-url <BASE_URL>  Base URL override. For `openai` "
        "this targets any OpenAI-compatible endpoint (LM Studio, vLLM, "
        "Ollama's /v1, llama.cpp, ...); for `ollama` this is the Ollama "
        "server address (default http://localhost:11434)\n"
        "      --api-key <API_KEY>  API key. Overrides the preset's "
        "`api_key`\n"
        "  -C, --cwd <CWD>  Working directory the agent's file and shell "
        "tools operate in\n"
        "      --preamble <PREAMBLE>  System preamble for the agent\n"
        "      --max-turns <MAX_TURNS>  Maximum model calls (including "
        "tool-call continuations) per user turn. `0` (the default) is "
        "unbounded\n"
        "      --max-retries <MAX_RETRIES>  Number of times a transient "
        "provider failure (timeout, 429, 5xx) is retried with exponential "
        "backoff before the turn fails. `0` disables retry\n"
        "      --context-limit <CONTEXT_LIMIT>  Model context window in "
        "tokens. `0` (the default) disables context compaction; a window "
        "reported by the provider's endpoint is adopted when available, "
        "otherwise this value is used\n"
        "      --compact-threshold <COMPACT_THRESHOLD>  Fraction of "
        "`context_limit` at which earlier context is summarized. `0` "
        "disables the tier; otherwise the value must be in `(0, 1]`\n"
        "      --clear-threshold <CLEAR_THRESHOLD>  Fraction of "
        "`context_limit` at which stale tool results are cleared. `0` "
        "disables the tier; otherwise the value must be in `(0, 1]`\n"
        "      --no-rubric-compaction  Disable the SelfCompact rubric "
        "probe that compacts the trajectory at a judged-safe point "
        "(independent of the token thresholds above)\n"
        "      --rubric-max-summaries <N>  Cap on rubric-triggered "
        "compactions per session. The default is `1` (the paper's cap); "
        "`0` means unlimited\n"
        "      --verbose  Verbose, structured logging to stderr (one JSON "
        "object per event: turn lifecycle, tool calls, compaction, "
        "retries, and errors)\n"
        "      --debug  Write the whole conversation history to "
        "`debug.json` (in the working directory) after every turn and "
        "again on exit\n"
        "      --skill-index-cap <SKILL_INDEX_CAP>  Maximum number of "
        "skills listed in the preamble's skills index\n"
        "      --shell-timeout-secs <SHELL_TIMEOUT_SECS>  `run_shell` "
        "timeout in seconds (the whole process tree is killed on expiry)\n"
        "      --max-output-chars <MAX_OUTPUT_CHARS>  Cap on tool/shell "
        "output text, in characters (longer is truncated)\n"
        "      --max-file-bytes <MAX_FILE_BYTES>  Cap on the size of a "
        "file `read_file` will read, in bytes\n"
        "      --resume <PATH>  Resume a session saved by `/save`: restore "
        "its conversation, model, preset, sub-agent, and working "
        "directory. The saved model/config values are authoritative, so "
        "`--model` / `--provider` / `--base-url` / `--api-key` are "
        "ignored when this is set\n"
        "      --allow-mcp  Trust and start MCP servers from .agents/mcp.json\n"
        "      --shell-allow <COMMAND>  Allow this run_shell command (repeatable)\n"
        "      --shell-deny <COMMAND>  Deny this run_shell command (repeatable)\n"
        "      --confirm-destructive  Prompt before recognized destructive shell commands\n"
        "      --no-confirm-destructive  Disable the destructive-command prompt\n"
        "  -h, --help  Print help\n"
        "  -V, --version  Print version\n",
        LLSH_VERSION);
}

static int parse_ulong(const char *s, unsigned long *out, char **err,
                        const char *flag) {
    /* strtoull silently accepts a leading '-' and wraps on overflow; reject
     * both explicitly so `--max-turns -1` does not become ULONG_MAX. */
    errno = 0;
    char *endp = NULL;
    unsigned long v = strtoull(s, &endp, 10);
    if (s[0] == '-' || endp == s || *endp != '\0' || errno == ERANGE) {
        if (err) {
            xbuf b;
            xbuf_init(&b);
            xbuf_fmt(&b, "invalid value for %s: `%s`", flag, s);
            *err = xbuf_steal(&b);
        }
        return -1;
    }
    *out = v;
    return 0;
}

static int parse_fraction_arg(const char *s, double *out, char **err,
                              const char *flag) {
    errno = 0;
    char *endp = NULL;
    double value = strtod(s, &endp);
    if (endp == s || *endp != '\0' || errno == ERANGE || !isfinite(value) ||
        value < 0.0 || value > 1.0) {
        if (err)
            *err = xstrfmt("invalid value for %s: `%s` (expected 0 or a finite value in (0, 1])",
                           flag, s);
        return -1;
    }
    *out = value;
    return 0;
}

int cli_parse(int argc, char **argv, cli *out, char **err) {
    memset(out, 0, sizeof *out);
    sl_init(&out->shell_allowlist);
    sl_init(&out->shell_denylist);

    enum {
        OPT_MODEL = 256,
        OPT_PROVIDER,
        OPT_BASE_URL,
        OPT_API_KEY,
        OPT_CWD,
        OPT_PREAMBLE,
        OPT_MAX_TURNS,
        OPT_MAX_RETRIES,
        OPT_CONTEXT_LIMIT,
        OPT_COMPACT_THRESHOLD,
        OPT_CLEAR_THRESHOLD,
        OPT_VERBOSE,
        OPT_DEBUG,
        OPT_NO_RUBRIC,
        OPT_RUBRIC_MAX,
        OPT_SKILL_INDEX_CAP,
        OPT_SHELL_TIMEOUT,
        OPT_MAX_OUTPUT,
        OPT_MAX_FILE,
        OPT_RESUME,
        OPT_ALLOW_MCP,
        OPT_SHELL_ALLOW,
        OPT_SHELL_DENY,
        OPT_CONFIRM_DESTRUCTIVE,
        OPT_NO_CONFIRM_DESTRUCTIVE,
    };
    static const struct option long_opts[] = {
        {"model", required_argument, 0, OPT_MODEL},
        {"provider", required_argument, 0, OPT_PROVIDER},
        {"base-url", required_argument, 0, OPT_BASE_URL},
        {"api-key", required_argument, 0, OPT_API_KEY},
        {"cwd", required_argument, 0, OPT_CWD},
        {"preamble", required_argument, 0, OPT_PREAMBLE},
        {"max-turns", required_argument, 0, OPT_MAX_TURNS},
        {"max-retries", required_argument, 0, OPT_MAX_RETRIES},
        {"context-limit", required_argument, 0, OPT_CONTEXT_LIMIT},
        {"compact-threshold", required_argument, 0, OPT_COMPACT_THRESHOLD},
        {"clear-threshold", required_argument, 0, OPT_CLEAR_THRESHOLD},
        {"verbose", no_argument, 0, OPT_VERBOSE},
        {"debug", no_argument, 0, OPT_DEBUG},
        {"no-rubric-compaction", no_argument, 0, OPT_NO_RUBRIC},
        {"rubric-max-summaries", required_argument, 0, OPT_RUBRIC_MAX},
        {"skill-index-cap", required_argument, 0, OPT_SKILL_INDEX_CAP},
        {"shell-timeout-secs", required_argument, 0, OPT_SHELL_TIMEOUT},
        {"max-output-chars", required_argument, 0, OPT_MAX_OUTPUT},
        {"max-file-bytes", required_argument, 0, OPT_MAX_FILE},
        {"resume", required_argument, 0, OPT_RESUME},
        {"allow-mcp", no_argument, 0, OPT_ALLOW_MCP},
        {"shell-allow", required_argument, 0, OPT_SHELL_ALLOW},
        {"shell-deny", required_argument, 0, OPT_SHELL_DENY},
        {"confirm-destructive", no_argument, 0, OPT_CONFIRM_DESTRUCTIVE},
        {"no-confirm-destructive", no_argument, 0, OPT_NO_CONFIRM_DESTRUCTIVE},
        {"help", no_argument, 0, 'h'},
        {"version", no_argument, 0, 'V'},
        {0, 0, 0, 0},
    };

    int c;
    int prompt_set = 0;
    optind = 1;
    while ((c = getopt_long(argc, argv, "C:hV", long_opts, NULL)) != -1) {
        switch (c) {
        case OPT_MODEL:
            out->model = xstrdup(optarg);
            break;
        case OPT_PROVIDER:
            out->provider = xstrdup(optarg);
            break;
        case OPT_BASE_URL:
            out->base_url = xstrdup(optarg);
            break;
        case OPT_API_KEY:
            out->api_key = xstrdup(optarg);
            break;
        case OPT_CWD:
        case 'C':
            out->cwd = xstrdup(optarg);
            break;
        case OPT_PREAMBLE:
            out->preamble = xstrdup(optarg);
            break;
        case OPT_MAX_TURNS:
            if (parse_ulong(optarg, &out->max_turns, err, "--max-turns") != 0)
                return -1;
            out->has_max_turns = true;
            break;
        case OPT_MAX_RETRIES:
            if (parse_ulong(optarg, &out->max_retries, err,
                            "--max-retries") != 0)
                return -1;
            out->has_max_retries = true;
            break;
        case OPT_CONTEXT_LIMIT:
            if (parse_ulong(optarg, &out->context_limit, err,
                            "--context-limit") != 0)
                return -1;
            out->has_context_limit = true;
            break;
        case OPT_COMPACT_THRESHOLD:
            if (parse_fraction_arg(optarg, &out->compact_threshold, err,
                                   "--compact-threshold") != 0)
                return -1;
            out->has_compact_threshold = true;
            break;
        case OPT_CLEAR_THRESHOLD:
            if (parse_fraction_arg(optarg, &out->clear_threshold, err,
                                   "--clear-threshold") != 0)
                return -1;
            out->has_clear_threshold = true;
            break;
        case OPT_VERBOSE:
            out->verbose = true;
            break;
        case OPT_DEBUG:
            out->debug = true;
            break;
        case OPT_NO_RUBRIC:
            out->no_rubric = true;
            break;
        case OPT_RUBRIC_MAX:
            if (parse_ulong(optarg, &out->rubric_max_summaries, err,
                            "--rubric-max-summaries") != 0)
                return -1;
            out->has_rubric_max_summaries = true;
            break;
        case OPT_SKILL_INDEX_CAP:
            if (parse_ulong(optarg, &out->skill_index_cap, err,
                            "--skill-index-cap") != 0)
                return -1;
            out->has_skill_index_cap = true;
            break;
        case OPT_SHELL_TIMEOUT:
            if (parse_ulong(optarg, &out->shell_timeout_secs, err,
                            "--shell-timeout-secs") != 0)
                return -1;
            out->has_shell_timeout_secs = true;
            break;
        case OPT_MAX_OUTPUT:
            if (parse_ulong(optarg, &out->max_output_chars, err,
                            "--max-output-chars") != 0)
                return -1;
            out->has_max_output_chars = true;
            break;
        case OPT_MAX_FILE:
            if (parse_ulong(optarg, &out->max_file_bytes, err,
                            "--max-file-bytes") != 0)
                return -1;
            out->has_max_file_bytes = true;
            break;
        case OPT_RESUME:
            out->resume = xstrdup(optarg);
            break;
        case OPT_ALLOW_MCP:
            out->allow_mcp = true;
            break;
        case OPT_SHELL_ALLOW:
            if (!optarg[0]) {
                if (err)
                    *err = xstrdup("--shell-allow requires a non-empty command");
                return -1;
            }
            sl_push_copy(&out->shell_allowlist, optarg);
            break;
        case OPT_SHELL_DENY:
            if (!optarg[0]) {
                if (err)
                    *err = xstrdup("--shell-deny requires a non-empty command");
                return -1;
            }
            sl_push_copy(&out->shell_denylist, optarg);
            break;
        case OPT_CONFIRM_DESTRUCTIVE:
            out->confirm_destructive = true;
            out->has_confirm_destructive = true;
            break;
        case OPT_NO_CONFIRM_DESTRUCTIVE:
            out->confirm_destructive = false;
            out->has_confirm_destructive = true;
            break;
        case 'h':
            print_usage(stdout);
            return CLI_HELP;
        case 'V':
            fprintf(stdout, "llsh %s\n", LLSH_VERSION);
            return CLI_HELP;
        case '?':
            print_usage(stderr);
            if (err)
                *err = xstrdup("try --help");
            return -1;
        default:
            /* getopt_long returns '?' for unknown options; anything else
             * here is a short option we did not register. */
            print_usage(stderr);
            if (err)
                *err = xstrdup("try --help");
            return -1;
        }
    }
    for (int i = optind; i < argc; i++) {
        if (prompt_set) {
            xbuf b;
            xbuf_init(&b);
            xbuf_fmt(&b, "unexpected argument `%s`", argv[i]);
            char *r = xbuf_steal(&b);
            if (err)
                *err = r;
            else
                free(r);
            return -1;
        }
        out->prompt = xstrdup(argv[i]);
        prompt_set = 1;
    }
    return 0;
}

void cli_free(cli *c) {
    free(c->prompt);
    free(c->model);
    free(c->provider);
    free(c->base_url);
    free(c->api_key);
    free(c->cwd);
    free(c->preamble);
    free(c->resume);
    sl_free(&c->shell_allowlist);
    sl_free(&c->shell_denylist);
}


/* ------------------------------------------------------------------ */
/* Merge + validation                                                  */
/* ------------------------------------------------------------------ */

static int validate_fraction(const char *name, double value, char **err) {
    if (value == 0.0)
        return 0;
    if (isnan(value) || isinf(value) || value <= 0.0 || value > 1.0) {
        if (err) {
            xbuf b;
            xbuf_init(&b);
            const char *rep;
            if (isnan(value))
                rep = "NaN";
            else if (value > 0)
                rep = "inf";
            else
                rep = "-inf";
            xbuf_fmt(&b, "%s must be 0 or in (0, 1], got %s", name, rep);
            *err = xbuf_steal(&b);
        }
        return -1;
    }
    return 0;
}

static int validate_compaction(const config *c, char **err) {
    if (validate_fraction("compact_threshold", c->compact_threshold, err) != 0)
        return -1;
    if (validate_fraction("clear_threshold", c->clear_threshold, err) != 0)
        return -1;
    if (c->context_limit > 0 && c->compact_threshold > 0.0 &&
        c->clear_threshold > 0.0 &&
        c->clear_threshold >= c->compact_threshold) {
        if (err) {
            char *ct = dtoa_dup(c->clear_threshold);
            char *pt = dtoa_dup(c->compact_threshold);
            xbuf b;
            xbuf_init(&b);
            xbuf_fmt(&b,
                     "clear_threshold (%s) must be less than "
                     "compact_threshold (%s)",
                     ct, pt);
            *err = xbuf_steal(&b);
            free(ct);
            free(pt);
        }
        return -1;
    }
    return 0;
}

int config_require_key_or_base(const config *c, char **err) {
    if (c->provider != PROV_OLLAMA && !c->base_url && !c->api_key) {
        if (err) {
            xbuf b;
            xbuf_init(&b);
            xbuf_fmt(&b,
                     "no API key for provider `%s`: set `api_key` in "
                     "`.agents/models.json` or pass --api-key",
                     provider_debug(c->provider));
            *err = xbuf_steal(&b);
        }
        return -1;
    }
    return 0;
}

void config_free(config *c) {
    free(c->model);
    free(c->base_url);
    free(c->api_key);
    free(c->preamble);
    sl_free(&c->shell_allowlist);
    sl_free(&c->shell_denylist);
}

int config_merge(const cli *cli, config *out, char **err) {
    memset(out, 0, sizeof *out);
    sl_init(&out->shell_allowlist);
    sl_init(&out->shell_denylist);
    out->confirm_destructive = cli->confirm_destructive;
    for (size_t i = 0; i < cli->shell_allowlist.len; i++)
        sl_push_copy(&out->shell_allowlist, cli->shell_allowlist.items[i]);
    for (size_t i = 0; i < cli->shell_denylist.len; i++)
        sl_push_copy(&out->shell_denylist, cli->shell_denylist.items[i]);

    out->provider = provider_parse(cli->provider ? cli->provider : "openai",
                                   err);
    if (err && *err)
        return -1;

    out->model = xstrdup(cli->model ? cli->model
                                    : provider_default_model(out->provider));

    out->base_url = cli->base_url ? xstrdup(cli->base_url) : NULL;
    out->api_key = cli->api_key ? xstrdup(cli->api_key) : NULL;

    out->preamble = cli->preamble ? xstrdup(cli->preamble)
                                  : default_preamble();

    out->max_turns = cli->has_max_turns ? cli->max_turns : 0;
    out->max_retries = cli->has_max_retries ? cli->max_retries
                                            : DEFAULT_MAX_RETRIES;
    out->context_limit =
        cli->has_context_limit ? cli->context_limit : 0;
    out->compact_threshold = cli->has_compact_threshold ? cli->compact_threshold
                                                        : DEFAULT_COMPACT_THRESHOLD;
    out->clear_threshold = cli->has_clear_threshold ? cli->clear_threshold
                                                     : DEFAULT_CLEAR_THRESHOLD;

    out->rubric_enabled = !cli->no_rubric;
    out->rubric_max_summaries = cli->has_rubric_max_summaries
                                    ? cli->rubric_max_summaries
                                    : RUBRIC_DEFAULT_MAX_SUMMARIES;

    out->verbose = cli->verbose;

    out->skill_index_cap =
        cli->has_skill_index_cap ? cli->skill_index_cap
                                 : DEFAULT_SKILL_INDEX_CAP;
    if (out->skill_index_cap < 1)
        out->skill_index_cap = 1;
    out->shell_timeout_secs =
        cli->has_shell_timeout_secs ? cli->shell_timeout_secs
                                    : DEFAULT_SHELL_TIMEOUT_SECS;
    if (out->shell_timeout_secs < 1)
        out->shell_timeout_secs = 1;
    out->max_output_chars =
        cli->has_max_output_chars ? cli->max_output_chars
                                  : DEFAULT_MAX_OUTPUT_CHARS;
    if (out->max_output_chars < 1)
        out->max_output_chars = 1;
    out->max_file_bytes =
        cli->has_max_file_bytes ? cli->max_file_bytes
                                : DEFAULT_MAX_FILE_BYTES;
    if (out->max_file_bytes < 1)
        out->max_file_bytes = 1;

    if (validate_compaction(out, err) != 0)
        return -1;
    /* The api_key/base_url requirement is checked by the caller AFTER a
     * models.json preset may have supplied them (precedence: CLI flag >
     * models.json preset > provider defaults). */
    return 0;
}

int config_from_cli(const cli *cli, config *out, char **err) {
    const char *cwd = cli->cwd ? cli->cwd : ".";

    if (config_merge(cli, out, err) != 0) {
        config_free(out);
        return -1;
    }

    char *cwd_exp = expand_tilde(cwd);
    if (chdir(cwd_exp) != 0) {
        if (err) {
            xbuf b;
            xbuf_init(&b);
            xbuf_fmt(&b, "failed to enter working directory `%s`: %s",
                     cwd_exp, strerror(errno));
            *err = xbuf_steal(&b);
        }
        free(cwd_exp);
        config_free(out);
        return -1;
    }
    free(cwd_exp);
    return 0;
}

/* ------------------------------------------------------------------ */
/* models.json presets                                                 */
/* ------------------------------------------------------------------ */

char *config_apply_models_preset(config *cfg, const models_file *models,
                                 const cli *cli, char **err) {
    const char *name = models->default_name;
    if (!name || !*name) {
        if (err)
            *err = xstrdup("models.json declares no `default` preset");
        return NULL;
    }
    const model_preset *preset = models_file_get(models, name);
    if (!preset) {
        if (err) {
            xbuf b;
            xbuf_init(&b);
            xbuf_put(&b, "models.json default preset `");
            xbuf_put(&b, name);
            xbuf_put(&b, "` is not in presets (");
            for (size_t i = 0; i < models->preset_count; i++) {
                if (i)
                    xbuf_put(&b, ", ");
                xbuf_put(&b, models->presets[i].name ? models->presets[i].name : "");
            }
            xbuf_put(&b, ")");
            *err = xbuf_steal(&b);
        }
        return NULL;
    }
    if (!cli->provider && preset->provider) {
        cfg->provider = provider_parse(preset->provider, err);
        if (err && *err)
            return NULL;
    }
    if (!cli->model && preset->model) {
        free(cfg->model);
        cfg->model = xstrdup(preset->model);
    }
    if (!cli->base_url && preset->base_url) {
        free(cfg->base_url);
        cfg->base_url = xstrdup(preset->base_url);
    }
    if (!cli->api_key && preset->api_key) {
        free(cfg->api_key);
        cfg->api_key = xstrdup(preset->api_key);
    }
    if (!cli->has_max_turns && preset->has_max_turns &&
        preset->max_turns > 0)
        cfg->max_turns = preset->max_turns;
    if (!cli->has_context_limit && preset->has_context_limit)
        cfg->context_limit = preset->context_limit;

    if (cfg->provider != PROV_OLLAMA && !cfg->base_url && !cfg->api_key) {
        if (err) {
            xbuf b;
            xbuf_init(&b);
            xbuf_fmt(&b,
                     "no API key for provider `%s` after applying preset "
                     "`%s`: set `api_key` in the preset/config file or "
                     "pass --api-key",
                     provider_debug(cfg->provider), name);
            *err = xbuf_steal(&b);
        }
        return NULL;
    }
    if (validate_compaction(cfg, err) != 0)
        return NULL;
    return xstrdup(name);
}