transcribe-cpp-sys 0.0.1

// transcribe-meta.h - shared GGUF KV reading helpers + post-load
// metadata reads (capabilities, languages).
//
// This header is INTERNAL. The public C ABI in include/transcribe.h
// knows nothing about gguf_context; the helpers here are how loader
// code and family handlers talk to a gguf_context once it's open.
//
// What lives here:
//
//   - KvResult: a tri-state {Absent, Ok, BadType} return type for
//     low-level KV readers. The whole point is to distinguish "the
//     converter didn't write this key" (Absent — usually fine for
//     optional keys) from "the converter wrote it with the wrong
//     type" (BadType — always a converter bug, surface as
//     TRANSCRIBE_ERR_GGUF). The original 2B implementation collapsed
//     these two into a single boolean and silently treated bad-type
//     optional KV as missing, which papered over real converter
//     mistakes.
//
//   - read_*_kv low-level helpers: one per scalar / string / string-
//     array KV type. Each returns KvResult and writes the parsed
//     value into an out parameter on Ok. On Absent or BadType the
//     out parameter is left untouched.
//
//   - read_capability_kv / read_languages_kv: post-load helpers that
//     family handlers call after applying their own family defaults.
//     Capabilities and languages are family-agnostic in the sense
//     that any family handler reads the same keys via the same
//     helpers; per-family code only fills in defaults for keys the
//     converter chose to omit.
//
// Why this is its own header instead of squatting on transcribe-loader.h:
// the loader is the "open a GGUF and identify it" object. These helpers
// are the "now that the GGUF is open, here is how shared metadata is
// read." Different jobs.

#pragma once

#include "transcribe.h"

#include <cstdint>
#include <string>
#include <vector>

struct gguf_context;
struct transcribe_model;

namespace transcribe {

// Tri-state result for a single GGUF KV read. The strict-now intent is
// that any consumer of these helpers explicitly handles BadType — the
// type system makes "I forgot about wrong type" a compile-time
// observation rather than a silent runtime fallback.
enum class KvResult {
    Absent,    // Key not present in the gguf.
    Ok,        // Key present, type matches expectation, value extracted.
    BadType,   // Key present but the GGUF type does not match. Always a
               // converter bug; callers should surface as TRANSCRIBE_ERR_GGUF.
};

// ---------------------------------------------------------------------------
// Low-level scalar / string / string-array readers
// ---------------------------------------------------------------------------
//
// Every helper takes the gguf_context, the key, and an out parameter.
// On Absent / BadType the out parameter is NOT modified, so callers can
// safely pre-populate a default and rely on the read leaving it alone
// when the key is missing.

KvResult read_string_kv(const gguf_context * ctx, const char * key,
                        std::string & out);

KvResult read_bool_kv  (const gguf_context * ctx, const char * key,
                        bool & out);

KvResult read_uint32_kv(const gguf_context * ctx, const char * key,
                        uint32_t & out);

KvResult read_int32_kv (const gguf_context * ctx, const char * key,
                        int32_t & out);

KvResult read_float32_kv(const gguf_context * ctx, const char * key,
                         float & out);

// Convenience: special-token id KV. The GGUF tokenizer schema has not
// standardized whether token ids are uint32 or int32 (different
// converters in the wider ecosystem use different types). This helper
// accepts either and casts to int. BadType only fires when the key is
// present and is neither uint32 nor int32.
KvResult read_token_id_kv(const gguf_context * ctx, const char * key,
                          int & out);

// String array. The destination vector is cleared and replaced with
// the parsed contents only on Ok. On Absent / BadType the destination
// is left untouched (caller's responsibility to pre-populate or
// post-validate).
KvResult read_string_array_kv(const gguf_context * ctx, const char * key,
                              std::vector<std::string> & out);

// int32 scalar array. Same Absent/Ok/BadType semantics as the other
// readers; the destination vector is replaced only on Ok. Used by the
// Parakeet TDT durations KV (`stt.parakeet.tdt.durations`); generic
// enough to live alongside the other low-level readers.
KvResult read_int32_array_kv(const gguf_context * ctx, const char * key,
                             std::vector<int32_t> & out);

// ---------------------------------------------------------------------------
// Higher-level required / optional KV helpers
// ---------------------------------------------------------------------------
//
// These sit on top of the low-level readers and fold
// KvResult → transcribe_status, logging diagnostics with a
// caller-supplied family tag. Every per-family weights.cpp was
// carrying its own copy of these; the only difference was the log
// prefix string.
//
// "Required" helpers: Absent and BadType both surface as
// TRANSCRIBE_ERR_GGUF. "Optional" helpers: Absent silently applies
// the caller's default; BadType is fatal (we control the converter).

transcribe_status read_required_u32_kv(const gguf_context * gguf,
                                       const char *         key,
                                       const char *         error_tag,
                                       int32_t &            out);

transcribe_status read_required_f32_kv(const gguf_context * gguf,
                                       const char *         key,
                                       const char *         error_tag,
                                       float &              out);

transcribe_status read_required_string_kv(const gguf_context * gguf,
                                          const char *         key,
                                          const char *         error_tag,
                                          std::string &        out);

transcribe_status read_optional_bool_kv(const gguf_context * gguf,
                                        const char *         key,
                                        const char *         error_tag,
                                        bool                 default_value,
                                        bool &               out);

transcribe_status read_optional_string_kv(const gguf_context * gguf,
                                          const char *         key,
                                          const char *         error_tag,
                                          const char *         default_value,
                                          std::string &        out);

transcribe_status read_optional_int32_kv(const gguf_context * gguf,
                                         const char *         key,
                                         const char *         error_tag,
                                         int32_t              default_value,
                                         int32_t &            out);

// ---------------------------------------------------------------------------
// Post-load shared metadata
// ---------------------------------------------------------------------------
//
// These are the "every family handler does this" pieces of post-load
// state population. They live here rather than in each family's
// arch/<family>/ directory because the schema (stt.capability.*,
// general.languages) is shared across families by design.

// Read all currently-recognized stt.capability.* boolean keys into
// caps, leaving fields untouched for absent keys. Callers should call
// this AFTER their own family-default population (apply_family_invariants
// or equivalent), so KV present overrides the family default and KV
// absent leaves the family default in place. This matches PLAN.md's
// "GGUF KV is authoritative; if a key is absent, the architecture
// supplies a default" rule.
//
// In 2B the recognized keys are stt.capability.translate,
// stt.capability.lang_detect, and stt.capability.streaming. The
// timestamp granularity capability fields are deliberately deferred
// until the public-header semantics are sharpened — see RESUME.md
// open question 4.
//
// Returns:
//   TRANSCRIBE_OK              on success or "all keys absent".
//   TRANSCRIBE_ERR_INVALID_ARG if gguf is null.
//   TRANSCRIBE_ERR_GGUF        if any recognized key is present with
//                              the wrong type.
transcribe_status read_capability_kv(const gguf_context *      gguf,
                                     transcribe_capabilities & caps);

// Read general.languages (string array of BCP-47-ish short codes) and
// install it on the model via transcribe_model::set_languages(). On
// Absent the model's language list is left unchanged (the caller is
// expected to pre-populate it as zero / nullptr — see the
// "information gap, not a claim" comment in arch/parakeet/model.cpp).
//
// Returns:
//   TRANSCRIBE_OK              on success or absent.
//   TRANSCRIBE_ERR_INVALID_ARG if gguf is null.
//   TRANSCRIBE_ERR_GGUF        if general.languages is present but is
//                              not a string array, or any element is
//                              null.
transcribe_status read_languages_kv(const gguf_context * gguf,
                                    transcribe_model &   model);

} // namespace transcribe