read pricing snapshot from CCUSAGE_PRICING_JSON_PATH

Error message

read pricing snapshot from CCUSAGE_PRICING_JSON_PATH

What it means

The ccusage-core build script panics with "read pricing snapshot from CCUSAGE_PRICING_JSON_PATH" when the CCUSAGE_PRICING_JSON_PATH environment variable is set but the file it points to cannot be read by fs::read_to_string — typically the file does not exist or is not readable. This env-var path lets builds embed a local LiteLLM pricing snapshot instead of fetching via flake.lock, so a bad path breaks the build immediately.

Source

Thrown at rust/crates/ccusage-core/build.rs:24

#[cfg(feature = "fetch-litellm-pricing")]
const LITELLM_PRICING_JSON: &str = "model_prices_and_context_window.json";
const OUT_PRICING_JSON: &str = "litellm-pricing.json.deflate";
const MODELS_DEV_PRICING_JSON: &str = "src/models-dev-pricing.json";
const OUT_MODELS_DEV_PRICING_JSON: &str = "models-dev-pricing.json.deflate";
const MODELS_DEV_CATALOG_RULES_JSON: &str = "src/models-dev-catalog-rules.json";
const OUT_MODELS_DEV_CATALOG_RULES_JSON: &str = "models-dev-catalog-rules.json.deflate";
const PRICING_JSON_PATH_ENV: &str = "CCUSAGE_PRICING_JSON_PATH";
#[cfg(feature = "fetch-litellm-pricing")]
const PRICING_FETCH_TIMEOUT_SECONDS: u64 = 10;

fn main() {
    println!("cargo:rerun-if-env-changed={PRICING_JSON_PATH_ENV}");

    let out_path = out_dir_path(OUT_PRICING_JSON);
    let pricing_json = if let Some(path) = env::var_os(PRICING_JSON_PATH_ENV) {
        let path = PathBuf::from(path);
        println!("cargo:rerun-if-changed={}", path.display());
        fs::read_to_string(path).expect("read pricing snapshot from CCUSAGE_PRICING_JSON_PATH")
    } else {
        println!("cargo:rerun-if-changed={FLAKE_LOCK_JSON}");
        fetch_pricing_json()
    };
    let pricing_json = compact_pricing_json(&pricing_json).expect("compact LiteLLM pricing JSON");

    fs::write(out_path, deflate(pricing_json.as_bytes()))
        .expect("write build-time pricing snapshot");

    embed_snapshot(MODELS_DEV_PRICING_JSON, OUT_MODELS_DEV_PRICING_JSON);
    embed_snapshot(
        MODELS_DEV_CATALOG_RULES_JSON,
        OUT_MODELS_DEV_CATALOG_RULES_JSON,
    );
}

/// The committed snapshots stay indented so their regeneration diffs stay
/// reviewable, but they are embedded verbatim, so the indentation - and, at

View on GitHub (pinned to afebc5d2e0)

Solutions

Verify the path exists: `ls -l "$CCUSAGE_PRICING_JSON_PATH"`; correct the env var or restore/download the snapshot file to that path.
Use an absolute path (or resolve it in CI before cargo runs) since the build script's CWD may differ from your shell's.
Check read permissions on the file and containing directories (`chmod a+r snapshot.json`).
Unset CCUSAGE_PRICING_JSON_PATH if you did not intend a local snapshot, letting the build fetch pricing via flake.lock instead.

Example fix

// before
export CCUSAGE_PRICING_JSON_PATH=./litellm_prices.json   # file not there
// after
export CCUSAGE_PRICING_JSON_PATH="$PWD/artifacts/litellm_prices.json"
ls -l "$CCUSAGE_PRICING_JSON_PATH" && cargo build

Defensive patterns

Strategy: validation

Validate before calling

[ -n "$CCUSAGE_PRICING_JSON_PATH" ] && [ -f "$CCUSAGE_PRICING_JSON_PATH" ] && [ -r "$CCUSAGE_PRICING_JSON_PATH" ] && echo OK || echo "set CCUSAGE_PRICING_JSON_PATH to an existing readable file (absolute path recommended)"

Try / catch

let pricing_json = match env::var_os(PRICING_JSON_PATH_ENV) {
    Some(p) => fs::read_to_string(PathBuf::from(&p))
        .unwrap_or_else(|e| panic!("read pricing snapshot from {PRICING_JSON_PATH_ENV}={}: {e}", p.to_string_lossy())),
    None => fetch_pricing_json(),
};

Prevention

Always use absolute paths for CCUSAGE_PRICING_JSON_PATH in CI and direnv configs
Add a build/CI step that downloads the snapshot before cargo runs, with an existence check
Unset the env var when you want the default flake.lock-based fetch instead
Keep the snapshot filename stable across artifact-generation steps

When it happens

Trigger: Building ccusage-core with CCUSAGE_PRICING_JSON_PATH set to a missing file, a directory, an unreadable file (permissions), or a path with a typo; also when the snapshot file was deleted or renamed after being exported in the environment or CI config.

Common situations: CI secret/config points at a path not checked out or downloaded in an earlier step; a developer sets the env var in .envrc/shell profile pointing to an old snapshot location; a relative path resolves against a different CWD during cargo build; file downloaded but under a different name.

Related errors

AI-assisted analysis of ccusage/ccusage@afebc5d2e0 (2026-09-02). Data as JSON: /api/errors/cdd3166ea4e3043f. Report an issue: GitHub.