ferrum-models 0.11.0

use std::fmt;
use std::fs::File;
use std::io::{BufReader, Read};
use std::path::{Path, PathBuf};
use std::sync::Arc;

use ferrum_interfaces::vnext::{
    FileFingerprint, ModelArtifactSourceRole, ModelSourceKind, OriginalModelSource,
    OriginalModelSources, ProductModelArtifactBinding, ProductModelSourceIdentity,
    ResolvedModelSource, ResolvedModelSources,
};
use ferrum_types::{FerrumError, Result};
use sha2::{Digest, Sha256};

const TOKENIZER_REQUIRED_FILES: &[&str] = &["tokenizer.json"];
const TOKENIZER_OPTIONAL_FILES: &[&str] = &[
    "tokenizer_config.json",
    "generation_config.json",
    "special_tokens_map.json",
    "chat_template.json",
    "chat_template.jinja",
];

/// Exact physical weight artifact selected by product source resolution.
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum ProductionWeightArtifact {
    SafetensorsDirectory(PathBuf),
    GgufFile(PathBuf),
}

#[derive(Debug, Clone, PartialEq, Eq)]
pub struct HuggingFaceSnapshotIdentity {
    pub repository_id: String,
    pub revision: String,
}

impl ProductionWeightArtifact {
    pub fn safetensors_directory(path: impl Into<PathBuf>) -> Self {
        Self::SafetensorsDirectory(path.into())
    }

    pub fn gguf_file(path: impl Into<PathBuf>) -> Self {
        Self::GgufFile(path.into())
    }

    pub fn path(&self) -> &Path {
        match self {
            Self::SafetensorsDirectory(path) | Self::GgufFile(path) => path,
        }
    }

    pub fn is_gguf(&self) -> bool {
        matches!(self, Self::GgufFile(_))
    }
}

/// Non-serialized product source lease shared by tokenizer, model preparation,
/// plan resolution, and the executor. Source roles remain distinct even when
/// all three happen to resolve to one Hugging Face snapshot.
#[derive(Clone)]
pub struct ProductionModelSourceBundle {
    semantic_root: PathBuf,
    tokenizer_root: PathBuf,
    weights: ProductionWeightArtifact,
    original_sources: OriginalModelSources,
    resolved_sources: ResolvedModelSources,
    config_json: Arc<[u8]>,
    weight_config_json: Option<Arc<[u8]>>,
    tokenizer_json: Arc<[u8]>,
    tokenizer_config_json: Option<Arc<[u8]>>,
    generation_config_json: Option<Arc<[u8]>>,
    chat_template_json: Option<Arc<[u8]>>,
    chat_template_jinja: Option<Arc<[u8]>>,
}

impl fmt::Debug for ProductionModelSourceBundle {
    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
        formatter
            .debug_struct("ProductionModelSourceBundle")
            .field("semantic_root", &self.semantic_root)
            .field("tokenizer_root", &self.tokenizer_root)
            .field("weights", &self.weights)
            .field("original_sources", &self.original_sources)
            .field("resolved_sources", &self.resolved_sources)
            .field("config_json_bytes", &self.config_json.len())
            .field(
                "weight_config_json_bytes",
                &self.weight_config_json.as_ref().map(|bytes| bytes.len()),
            )
            .field("tokenizer_json_bytes", &self.tokenizer_json.len())
            .field(
                "tokenizer_config_json_bytes",
                &self.tokenizer_config_json.as_ref().map(|bytes| bytes.len()),
            )
            .field(
                "generation_config_json_bytes",
                &self
                    .generation_config_json
                    .as_ref()
                    .map(|bytes| bytes.len()),
            )
            .field(
                "chat_template_json_bytes",
                &self.chat_template_json.as_ref().map(|bytes| bytes.len()),
            )
            .field(
                "chat_template_jinja_bytes",
                &self.chat_template_jinja.as_ref().map(|bytes| bytes.len()),
            )
            .finish()
    }
}

impl ProductionModelSourceBundle {
    pub fn open(
        semantic_root: impl AsRef<Path>,
        tokenizer_root: impl AsRef<Path>,
        weights: ProductionWeightArtifact,
        original_sources: OriginalModelSources,
    ) -> Result<Self> {
        Self::open_with_semantic_preflight(
            semantic_root,
            tokenizer_root,
            weights,
            original_sources,
            |_| Ok(()),
        )
    }

    /// Opens one immutable role-specific bundle after validating the exact
    /// semantic bytes retained by the bundle. The preflight runs before the
    /// weight path is normalized, listed, fingerprinted, or opened.
    pub(super) fn open_with_semantic_preflight(
        semantic_root: impl AsRef<Path>,
        tokenizer_root: impl AsRef<Path>,
        weights: ProductionWeightArtifact,
        original_sources: OriginalModelSources,
        semantic_preflight: impl FnOnce(&[u8]) -> Result<()>,
    ) -> Result<Self> {
        let semantic_root = canonical_directory(semantic_root.as_ref(), "semantic source")?;
        let config_json = read_required_file(&semantic_root.join("config.json"))?;
        semantic_preflight(&config_json)?;

        let tokenizer_root = canonical_directory(tokenizer_root.as_ref(), "tokenizer source")?;
        let weights = normalize_weight_artifact(weights)?;

        let semantic_files = vec![fingerprint_loaded_file("config.json", &config_json)?];
        let tokenizer_files = fingerprint_named_files(
            &tokenizer_root,
            TOKENIZER_REQUIRED_FILES,
            TOKENIZER_OPTIONAL_FILES,
        )?;
        let weight_files = fingerprint_weight_artifact(&weights)?;

        let weight_config_json = match &weights {
            ProductionWeightArtifact::SafetensorsDirectory(root) => {
                read_optional_file(&root.join("config.json"))?
            }
            ProductionWeightArtifact::GgufFile(_) => None,
        };
        let tokenizer_json = read_required_file(&tokenizer_root.join("tokenizer.json"))?;
        let tokenizer_config_json =
            read_optional_file(&tokenizer_root.join("tokenizer_config.json"))?;
        let generation_config_json =
            read_optional_file(&tokenizer_root.join("generation_config.json"))?;
        let chat_template_json = read_optional_file(&tokenizer_root.join("chat_template.json"))?;
        let chat_template_jinja = read_optional_file(&tokenizer_root.join("chat_template.jinja"))?;

        let resolved_sources = ResolvedModelSources {
            semantic: resolved_source(&original_sources.semantic, &semantic_root, semantic_files)?,
            tokenizer: resolved_source(
                &original_sources.tokenizer,
                &tokenizer_root,
                tokenizer_files,
            )?,
            weights: resolved_source(&original_sources.weights, weights.path(), weight_files)?,
        };

        Ok(Self {
            semantic_root,
            tokenizer_root,
            weights,
            original_sources,
            resolved_sources,
            config_json,
            weight_config_json,
            tokenizer_json,
            tokenizer_config_json,
            generation_config_json,
            chat_template_json,
            chat_template_jinja,
        })
    }

    /// Compatibility constructor for existing co-located safetensors callers.
    /// Product entrypoints should construct explicit role-specific sources.
    pub fn open_colocated_safetensors(model_dir: impl AsRef<Path>) -> Result<Self> {
        let model_dir = model_dir.as_ref();
        let location = model_dir.display().to_string();
        let original = OriginalModelSource {
            kind: ModelSourceKind::LocalDirectory,
            location,
            requested_revision: None,
        };
        Self::open(
            model_dir,
            model_dir,
            ProductionWeightArtifact::safetensors_directory(model_dir),
            OriginalModelSources {
                semantic: original.clone(),
                tokenizer: original.clone(),
                weights: original,
            },
        )
    }

    pub fn semantic_root(&self) -> &Path {
        &self.semantic_root
    }

    pub fn tokenizer_root(&self) -> &Path {
        &self.tokenizer_root
    }

    pub fn tokenizer_file(&self) -> PathBuf {
        self.tokenizer_root.join("tokenizer.json")
    }

    pub fn weights(&self) -> &ProductionWeightArtifact {
        &self.weights
    }

    pub fn original_sources(&self) -> &OriginalModelSources {
        &self.original_sources
    }

    pub fn resolved_sources(&self) -> &ResolvedModelSources {
        &self.resolved_sources
    }

    pub fn config_json(&self) -> &[u8] {
        &self.config_json
    }

    pub fn tokenizer_json(&self) -> &[u8] {
        &self.tokenizer_json
    }

    /// Physical checkpoint metadata retained independently from the semantic
    /// model config. Quantized safetensors commonly repeat semantic fields in
    /// this file, but only physical format metadata may be selected from it.
    pub fn weight_config_json(&self) -> Option<&[u8]> {
        self.weight_config_json.as_deref()
    }

    pub fn tokenizer_config_json(&self) -> Option<&[u8]> {
        self.tokenizer_config_json.as_deref()
    }

    pub fn generation_config_json(&self) -> Option<&[u8]> {
        self.generation_config_json.as_deref()
    }

    pub fn chat_template_json(&self) -> Option<&[u8]> {
        self.chat_template_json.as_deref()
    }

    pub fn chat_template_jinja(&self) -> Option<&[u8]> {
        self.chat_template_jinja.as_deref()
    }

    pub fn fingerprint(
        &self,
        role: ModelArtifactSourceRole,
        relative_path: &str,
    ) -> Option<&FileFingerprint> {
        self.resolved_sources
            .for_role(role)
            .files
            .iter()
            .find(|file| file.relative_path == relative_path)
    }

    pub fn weight_payload_bytes(&self) -> Result<u64> {
        self.resolved_sources
            .weights
            .files
            .iter()
            .filter(|file| {
                file.relative_path.ends_with(".safetensors")
                    // A GGUF artifact contributes exactly its one selected file.
                    || self.weights.is_gguf()
            })
            .try_fold(0_u64, |total, file| {
                total.checked_add(file.size_bytes).ok_or_else(|| {
                    FerrumError::model("resolved weight payload byte size overflows u64")
                })
            })
    }

    pub fn product_source_identity(
        &self,
        requested_model: impl Into<String>,
        resolved_model: impl Into<String>,
        template_source_file: &str,
        template_content: &str,
    ) -> Result<ProductModelSourceIdentity> {
        let binding = |role, source_file: &str, content_sha256: Option<String>| {
            let fingerprint = self.fingerprint(role, source_file).ok_or_else(|| {
                FerrumError::model(format!(
                    "selected {role:?} source file is absent: {source_file}"
                ))
            })?;
            ProductModelArtifactBinding::new(
                role,
                source_file,
                fingerprint.sha256.clone(),
                content_sha256,
            )
            .map_err(|error| FerrumError::model(error.to_string()))
        };
        let semantic_config = binding(ModelArtifactSourceRole::Semantic, "config.json", None)?;
        let tokenizer = binding(ModelArtifactSourceRole::Tokenizer, "tokenizer.json", None)?;
        let template = binding(
            ModelArtifactSourceRole::Tokenizer,
            template_source_file,
            Some(format!("{:x}", Sha256::digest(template_content.as_bytes()))),
        )?;
        let weight_config = self
            .weight_config_json
            .as_ref()
            .map(|_| binding(ModelArtifactSourceRole::Weights, "config.json", None))
            .transpose()?;
        ProductModelSourceIdentity::new(
            requested_model,
            resolved_model,
            self.original_sources.clone(),
            self.resolved_sources.clone(),
            semantic_config,
            tokenizer,
            template,
            weight_config,
        )
        .map_err(|error| FerrumError::model(error.to_string()))
    }
}

fn canonical_directory(path: &Path, kind: &str) -> Result<PathBuf> {
    if !path.is_dir() {
        return Err(FerrumError::model(format!(
            "{kind} is not a directory: {}",
            path.display()
        )));
    }
    path.canonicalize()
        .map_err(|error| FerrumError::model(format!("canonicalize {}: {error}", path.display())))
}

fn normalize_weight_artifact(
    artifact: ProductionWeightArtifact,
) -> Result<ProductionWeightArtifact> {
    match artifact {
        ProductionWeightArtifact::SafetensorsDirectory(path) => {
            Ok(ProductionWeightArtifact::SafetensorsDirectory(
                canonical_directory(&path, "safetensors weight source")?,
            ))
        }
        ProductionWeightArtifact::GgufFile(path) => {
            if !path.is_file() {
                return Err(FerrumError::model(format!(
                    "GGUF weight source is not a file: {}",
                    path.display()
                )));
            }
            let file_name = path.file_name().ok_or_else(|| {
                FerrumError::model(format!("GGUF source has no file name: {}", path.display()))
            })?;
            let parent = path.parent().ok_or_else(|| {
                FerrumError::model(format!("GGUF source has no parent: {}", path.display()))
            })?;
            let parent = parent.canonicalize().map_err(|error| {
                FerrumError::model(format!("canonicalize {}: {error}", parent.display()))
            })?;
            Ok(ProductionWeightArtifact::GgufFile(parent.join(file_name)))
        }
    }
}

fn fingerprint_named_files(
    root: &Path,
    required: &[&str],
    optional: &[&str],
) -> Result<Vec<FileFingerprint>> {
    let mut files = Vec::with_capacity(required.len() + optional.len());
    for relative_path in required {
        files.push(fingerprint_file(root, relative_path)?);
    }
    for relative_path in optional {
        if root.join(relative_path).is_file() {
            files.push(fingerprint_file(root, relative_path)?);
        }
    }
    files.sort_by(|left, right| left.relative_path.cmp(&right.relative_path));
    Ok(files)
}

fn fingerprint_weight_artifact(
    artifact: &ProductionWeightArtifact,
) -> Result<Vec<FileFingerprint>> {
    match artifact {
        ProductionWeightArtifact::GgufFile(path) => {
            let parent = path
                .parent()
                .ok_or_else(|| FerrumError::model("GGUF source has no parent"))?;
            // Repository evidence must distinguish subdirectories containing
            // the same basename. Preserve the snapshot path before LFS resolution.
            let root = if huggingface_snapshot_identity(path).is_some() {
                path.ancestors()
                    .find(|root| huggingface_snapshot_root_identity(root).is_some())
                    .unwrap_or(parent)
            } else {
                parent
            };
            let relative = path.strip_prefix(root).map_err(|error| {
                FerrumError::model(format!("GGUF artifact is outside its source root: {error}"))
            })?;
            let name = relative
                .to_str()
                .ok_or_else(|| FerrumError::model("GGUF source file name is not UTF-8"))?
                .replace(std::path::MAIN_SEPARATOR, "/");
            fingerprint_file(root, &name).map(|file| vec![file])
        }
        ProductionWeightArtifact::SafetensorsDirectory(root) => {
            let mut relative_paths = std::fs::read_dir(root)
                .map_err(|error| {
                    FerrumError::model(format!("read weight directory {}: {error}", root.display()))
                })?
                .filter_map(|entry| entry.ok())
                .filter_map(|entry| {
                    let path = entry.path();
                    let name = path.file_name()?.to_str()?.to_owned();
                    (path.is_file()
                        && (name.ends_with(".safetensors")
                            || name == "model.safetensors.index.json"
                            || name == "config.json"))
                        .then_some(name)
                })
                .collect::<Vec<_>>();
            relative_paths.sort();
            if !relative_paths
                .iter()
                .any(|path| path.ends_with(".safetensors"))
            {
                return Err(FerrumError::model(format!(
                    "safetensors source contains no shard: {}",
                    root.display()
                )));
            }
            relative_paths
                .iter()
                .map(|path| fingerprint_file(root, path))
                .collect()
        }
    }
}

fn fingerprint_file(root: &Path, relative_path: &str) -> Result<FileFingerprint> {
    if !portable_relative_path(relative_path) {
        return Err(FerrumError::model(format!(
            "source manifest path is not portable: {relative_path:?}"
        )));
    }
    let path = root.join(relative_path);
    let metadata = std::fs::metadata(&path)
        .map_err(|error| FerrumError::model(format!("stat {}: {error}", path.display())))?;
    if !metadata.is_file() || metadata.len() == 0 {
        return Err(FerrumError::model(format!(
            "source manifest file is missing or empty: {}",
            path.display()
        )));
    }
    // Cache object names may be Xet IDs rather than SHA256 content digests.
    // Fingerprint the bytes consumed by every source, including HF snapshots.
    let sha256 = hash_file(&path)?;
    Ok(FileFingerprint {
        relative_path: relative_path.to_owned(),
        size_bytes: metadata.len(),
        sha256,
    })
}

fn fingerprint_loaded_file(relative_path: &str, bytes: &[u8]) -> Result<FileFingerprint> {
    if !portable_relative_path(relative_path) {
        return Err(FerrumError::model(format!(
            "source manifest path is not portable: {relative_path:?}"
        )));
    }
    if bytes.is_empty() {
        return Err(FerrumError::model(format!(
            "source manifest file is empty: {relative_path}"
        )));
    }
    let size_bytes = u64::try_from(bytes.len())
        .map_err(|_| FerrumError::internal("source file size exceeds u64"))?;
    Ok(FileFingerprint {
        relative_path: relative_path.to_owned(),
        size_bytes,
        sha256: format!("{:x}", Sha256::digest(bytes)),
    })
}

fn hash_file(path: &Path) -> Result<String> {
    let started = std::time::Instant::now();
    let file = File::open(path)
        .map_err(|error| FerrumError::model(format!("open {}: {error}", path.display())))?;
    let mut reader = BufReader::with_capacity(4 * 1024 * 1024, file);
    let mut hasher = Sha256::new();
    let mut buffer = vec![0_u8; 4 * 1024 * 1024];
    let mut bytes_hashed = 0_u64;
    loop {
        let count = reader
            .read(&mut buffer)
            .map_err(|error| FerrumError::model(format!("read {}: {error}", path.display())))?;
        if count == 0 {
            break;
        }
        hasher.update(&buffer[..count]);
        bytes_hashed = bytes_hashed.saturating_add(count as u64);
    }
    let fingerprint = format!("{:x}", hasher.finalize());
    tracing::debug!(
        target: "ferrum.startup",
        phase = "source_fingerprint",
        source_path = %path.display(),
        bytes_hashed,
        duration_us = started.elapsed().as_micros() as u64,
        "Product source content fingerprint completed"
    );
    Ok(fingerprint)
}

fn resolved_source(
    original: &OriginalModelSource,
    path: &Path,
    files: Vec<FileFingerprint>,
) -> Result<ResolvedModelSource> {
    let manifest_revision = manifest_revision(&files)?;
    let snapshot_identity = huggingface_snapshot_identity(path);
    let (canonical_location, resolved_revision) = if let Some(identity) = snapshot_identity {
        (identity.repository_id, identity.revision)
    } else {
        match original.kind {
            ModelSourceKind::Repository => (
                original.location.clone(),
                huggingface_snapshot_revision(path).ok_or_else(|| {
                    FerrumError::model(format!(
                        "repository source {} did not resolve below snapshots/<revision>: {}",
                        original.location,
                        path.display()
                    ))
                })?,
            ),
            ModelSourceKind::LocalDirectory | ModelSourceKind::LocalFile => {
                (path.display().to_string(), manifest_revision)
            }
            ModelSourceKind::ReleaseArtifact => {
                return Err(FerrumError::unsupported(
                    "release artifact source bundles are not implemented",
                ))
            }
        }
    };
    Ok(ResolvedModelSource {
        canonical_location,
        resolved_revision,
        files,
    })
}

/// Recover a stable repository/revision identity only from an exact Hugging
/// Face cache snapshot root or an artifact below it. Nested artifact directories
/// retain the same snapshot identity; ambiguous nested cache roots are rejected.
/// The path is
/// inspected structurally without canonicalizing an LFS symlink into `blobs/`.
pub fn huggingface_snapshot_identity(path: &Path) -> Option<HuggingFaceSnapshotIdentity> {
    if path
        .components()
        .any(|part| matches!(part, std::path::Component::ParentDir))
    {
        return None;
    }
    let mut identities = path
        .ancestors()
        .filter_map(huggingface_snapshot_root_identity);
    let identity = identities.next()?;
    identities.next().is_none().then_some(identity)
}

fn huggingface_snapshot_root_identity(root: &Path) -> Option<HuggingFaceSnapshotIdentity> {
    let revision = root.file_name()?.to_str()?;
    if revision.len() != 40
        || !revision
            .bytes()
            .all(|byte| byte.is_ascii_digit() || (b'a'..=b'f').contains(&byte))
    {
        return None;
    }
    let snapshots = root.parent()?;
    if snapshots.file_name()?.to_str()? != "snapshots" {
        return None;
    }
    let repository_dir = snapshots.parent()?.file_name()?.to_str()?;
    let encoded = repository_dir.strip_prefix("models--")?;
    let components = encoded.split("--").collect::<Vec<_>>();
    if components.len() != 2 || components.iter().any(|component| component.is_empty()) {
        return None;
    }
    let repository_id = components.join("/");
    if format!("models--{}", repository_id.replace('/', "--")) != repository_dir {
        return None;
    }
    Some(HuggingFaceSnapshotIdentity {
        repository_id,
        revision: revision.to_owned(),
    })
}

fn huggingface_snapshot_revision(path: &Path) -> Option<String> {
    let root = if path.is_file() { path.parent()? } else { path };
    if root.parent()?.file_name()?.to_str()? != "snapshots" {
        return None;
    }
    root.file_name()?.to_str().map(str::to_owned)
}

fn manifest_revision(files: &[FileFingerprint]) -> Result<String> {
    let bytes = serde_json::to_vec(files)
        .map_err(|error| FerrumError::internal(format!("serialize source manifest: {error}")))?;
    Ok(format!("{:x}", Sha256::digest(bytes)))
}

fn read_required_file(path: &Path) -> Result<Arc<[u8]>> {
    let bytes = std::fs::read(path)
        .map_err(|error| FerrumError::model(format!("read {}: {error}", path.display())))?;
    if bytes.is_empty() {
        return Err(FerrumError::model(format!(
            "required source file is empty: {}",
            path.display()
        )));
    }
    Ok(bytes.into())
}

fn read_optional_file(path: &Path) -> Result<Option<Arc<[u8]>>> {
    if !path.is_file() {
        return Ok(None);
    }
    read_required_file(path).map(Some)
}

fn portable_relative_path(path: &str) -> bool {
    !path.is_empty()
        && !path.starts_with('/')
        && !path.ends_with('/')
        && !path.contains('\\')
        && path
            .split('/')
            .all(|component| !matches!(component, "" | "." | ".."))
}

#[cfg(test)]
mod tests {
    use super::*;

    fn original(kind: ModelSourceKind, location: &str) -> OriginalModelSource {
        OriginalModelSource {
            kind,
            location: location.to_owned(),
            requested_revision: None,
        }
    }

    #[test]
    fn preserves_three_distinct_roots_and_same_named_files() {
        let root = tempfile::tempdir().unwrap();
        let semantic = root.path().join("semantic");
        let tokenizer = root.path().join("tokenizer");
        let weights = root.path().join("weights");
        std::fs::create_dir_all(&semantic).unwrap();
        std::fs::create_dir_all(&tokenizer).unwrap();
        std::fs::create_dir_all(&weights).unwrap();
        std::fs::write(
            semantic.join("config.json"),
            br#"{"architectures":["Fixture"]}"#,
        )
        .unwrap();
        std::fs::write(tokenizer.join("tokenizer.json"), br#"{"version":"1.0"}"#).unwrap();
        std::fs::write(
            tokenizer.join("tokenizer_config.json"),
            br#"{"chat_template":"fixture"}"#,
        )
        .unwrap();
        std::fs::write(weights.join("model.safetensors"), b"fixture-weights").unwrap();

        let bundle = ProductionModelSourceBundle::open(
            &semantic,
            &tokenizer,
            ProductionWeightArtifact::safetensors_directory(&weights),
            OriginalModelSources {
                semantic: original(ModelSourceKind::LocalDirectory, "semantic-input"),
                tokenizer: original(ModelSourceKind::LocalDirectory, "tokenizer-input"),
                weights: original(ModelSourceKind::LocalDirectory, "weights-input"),
            },
        )
        .unwrap();

        assert_ne!(bundle.semantic_root(), bundle.tokenizer_root());
        assert_ne!(bundle.tokenizer_root(), bundle.weights().path());
        assert_eq!(
            bundle
                .fingerprint(ModelArtifactSourceRole::Semantic, "config.json")
                .unwrap()
                .size_bytes,
            29
        );
        assert!(bundle
            .fingerprint(ModelArtifactSourceRole::Tokenizer, "tokenizer.json")
            .is_some());
        assert!(bundle
            .fingerprint(ModelArtifactSourceRole::Weights, "model.safetensors")
            .is_some());
        assert_eq!(bundle.weight_payload_bytes().unwrap(), 15);
    }

    #[test]
    fn semantic_preflight_fingerprint_and_retained_bytes_are_atomic() {
        let root = tempfile::tempdir().unwrap();
        let semantic = root.path().join("semantic");
        let tokenizer = root.path().join("tokenizer");
        let weights = root.path().join("weights");
        std::fs::create_dir_all(&semantic).unwrap();
        std::fs::create_dir_all(&tokenizer).unwrap();
        std::fs::create_dir_all(&weights).unwrap();
        let original_config = br#"{"architectures":["Original"]}"#;
        std::fs::write(semantic.join("config.json"), original_config).unwrap();
        std::fs::write(tokenizer.join("tokenizer.json"), br#"{"version":"1.0"}"#).unwrap();
        std::fs::write(weights.join("model.safetensors"), b"fixture-weights").unwrap();

        let bundle = ProductionModelSourceBundle::open_with_semantic_preflight(
            &semantic,
            &tokenizer,
            ProductionWeightArtifact::safetensors_directory(&weights),
            OriginalModelSources {
                semantic: original(ModelSourceKind::LocalDirectory, "semantic-input"),
                tokenizer: original(ModelSourceKind::LocalDirectory, "tokenizer-input"),
                weights: original(ModelSourceKind::LocalDirectory, "weights-input"),
            },
            |raw| {
                assert_eq!(raw, original_config);
                std::fs::write(
                    semantic.join("config.json"),
                    br#"{"architectures":["Mutated"]}"#,
                )
                .unwrap();
                Ok(())
            },
        )
        .unwrap();

        assert_eq!(bundle.config_json(), original_config);
        assert_eq!(
            bundle
                .fingerprint(ModelArtifactSourceRole::Semantic, "config.json")
                .unwrap()
                .sha256,
            format!("{:x}", Sha256::digest(original_config))
        );
    }

    #[test]
    fn local_huggingface_snapshot_paths_recover_stable_role_identities() {
        let root = tempfile::tempdir().unwrap();
        let semantic_revision = "a".repeat(40);
        let weight_revision = "b".repeat(40);
        let semantic = root
            .path()
            .join("models--Qwen--Qwen3.5-35B-A3B")
            .join("snapshots")
            .join(&semantic_revision);
        let weights = root
            .path()
            .join("models--Qwen--Qwen3.5-35B-A3B-GPTQ-Int4")
            .join("snapshots")
            .join(&weight_revision);
        std::fs::create_dir_all(&semantic).unwrap();
        std::fs::create_dir_all(&weights).unwrap();
        std::fs::write(
            semantic.join("config.json"),
            br#"{"architectures":["Fixture"]}"#,
        )
        .unwrap();
        std::fs::write(semantic.join("tokenizer.json"), br#"{"version":"1.0"}"#).unwrap();
        std::fs::write(
            semantic.join("tokenizer_config.json"),
            br#"{"chat_template":"fixture"}"#,
        )
        .unwrap();
        std::fs::write(
            weights.join("config.json"),
            br#"{"quantization_config":{"quant_method":"gptq"}}"#,
        )
        .unwrap();
        std::fs::write(weights.join("model.safetensors"), b"fixture-weights").unwrap();
        let local = |path: &Path| OriginalModelSource {
            kind: ModelSourceKind::LocalDirectory,
            location: path.display().to_string(),
            requested_revision: None,
        };
        let bundle = ProductionModelSourceBundle::open(
            &semantic,
            &semantic,
            ProductionWeightArtifact::safetensors_directory(&weights),
            OriginalModelSources {
                semantic: local(&semantic),
                tokenizer: local(&semantic),
                weights: local(&weights),
            },
        )
        .unwrap();

        assert_eq!(
            bundle.resolved_sources().semantic.canonical_location,
            "Qwen/Qwen3.5-35B-A3B"
        );
        assert_eq!(
            bundle.resolved_sources().semantic.resolved_revision,
            semantic_revision
        );
        assert_eq!(
            bundle.resolved_sources().weights.canonical_location,
            "Qwen/Qwen3.5-35B-A3B-GPTQ-Int4"
        );
        assert_eq!(
            bundle.resolved_sources().weights.resolved_revision,
            weight_revision
        );
        let identity = bundle
            .product_source_identity(
                weights.display().to_string(),
                "Qwen/Qwen3.5-35B-A3B-GPTQ-Int4",
                "tokenizer_config.json",
                "fixture",
            )
            .unwrap();
        let template_sha256 = format!("{:x}", Sha256::digest(b"fixture"));
        assert_eq!(identity.template.content_sha256, Some(template_sha256));
        assert!(identity.weight_config.is_some());
    }

    #[test]
    fn huggingface_snapshot_identity_rejects_ambiguous_cache_paths() {
        let revision = "a".repeat(40);
        assert!(huggingface_snapshot_identity(Path::new(&format!(
            "/cache/models--Qwen--Model/snapshots/{revision}"
        )))
        .is_some());
        assert!(huggingface_snapshot_identity(Path::new(
            "/cache/models--Qwen--Model/snapshots/main"
        ))
        .is_none());
        assert!(huggingface_snapshot_identity(Path::new(&format!(
            "/cache/models--Qwen--Nested--Model/snapshots/{revision}"
        )))
        .is_none());
        let root = PathBuf::from(format!("/cache/models--Owner--Model/snapshots/{revision}"));
        let nested = huggingface_snapshot_identity(&root.join("weights/quant/model.gguf")).unwrap();
        assert_eq!(nested.repository_id, "Owner/Model");
        assert_eq!(nested.revision, revision);
        assert!(huggingface_snapshot_identity(&root.join("../other/model.gguf")).is_none());
        assert!(huggingface_snapshot_identity(&root.join(format!(
            "models--Other--Model/snapshots/{revision}/model.gguf"
        )))
        .is_none());
    }

    #[cfg(unix)]
    #[test]
    fn huggingface_cache_ids_do_not_substitute_for_content_fingerprints() {
        use std::os::unix::fs::symlink;

        let root = tempfile::tempdir().unwrap();
        let repository = root.path().join("models--fixture--weights");
        let blobs = repository.join("blobs");
        let snapshot = repository.join("snapshots").join("revision");
        std::fs::create_dir_all(&blobs).unwrap();
        std::fs::create_dir_all(&snapshot).unwrap();
        let object_id = "a".repeat(64);
        std::fs::write(blobs.join(&object_id), b"abc").unwrap();
        symlink(
            Path::new("../../blobs").join(&object_id),
            snapshot.join("model.safetensors"),
        )
        .unwrap();

        let fingerprint = fingerprint_file(&snapshot, "model.safetensors").unwrap();
        // Standard SHA256 known answer, independent of the cache locator.
        assert_eq!(
            fingerprint.sha256,
            "ba7816bf8f01cfea414140de5dae2223b00361a396177a9cb410ff61f20015ad"
        );
        assert_eq!(fingerprint.size_bytes, 3);
        std::fs::write(blobs.join(&object_id), b"abd").unwrap();
        let changed = fingerprint_file(&snapshot, "model.safetensors").unwrap();
        assert_eq!(changed.size_bytes, fingerprint.size_bytes);
        assert_ne!(changed.sha256, fingerprint.sha256);
    }

    #[cfg(unix)]
    #[test]
    fn product_package_and_direct_blob_links_have_the_same_content_identity() {
        use std::os::unix::fs::symlink;

        let root = tempfile::tempdir().unwrap();
        let repository = root.path().join("models--fixture--Qwen3.5-4B-GGUF");
        let blobs = repository.join("blobs");
        let snapshot = repository.join("snapshots").join("revision");
        let package = root.path().join("product-package");
        std::fs::create_dir_all(&blobs).unwrap();
        std::fs::create_dir_all(&snapshot).unwrap();
        std::fs::create_dir_all(&package).unwrap();
        let digest = "b".repeat(64);
        std::fs::write(blobs.join(&digest), b"weight-bytes").unwrap();
        let snapshot_weight = snapshot.join("model.gguf");
        symlink(Path::new("../../blobs").join(&digest), &snapshot_weight).unwrap();
        symlink(&snapshot_weight, package.join("model.gguf")).unwrap();

        let fingerprint = fingerprint_file(&package, "model.gguf").unwrap();
        assert_eq!(
            fingerprint.sha256,
            format!("{:x}", Sha256::digest(b"weight-bytes"))
        );
        assert_eq!(fingerprint.size_bytes, 12);

        let direct_blob_link = package.join("direct-blob.gguf");
        symlink(blobs.join(&digest), &direct_blob_link).unwrap();
        let direct_blob_fingerprint = fingerprint_file(&package, "direct-blob.gguf").unwrap();
        assert_eq!(
            direct_blob_fingerprint.sha256,
            format!("{:x}", Sha256::digest(b"weight-bytes"))
        );
        assert_eq!(direct_blob_fingerprint.sha256, fingerprint.sha256);
    }
}