BoundaryML/baml · error

BAML_CACHE_VERIFY: cached stdlib interface for package

Error message

BAML_CACHE_VERIFY: cached stdlib interface for package `{name}` differs from a fresh derivation ({} vs {} bytes). The cached typed interface is a stale or incomplete substitute — please report this.

What it means

Error "BAML_CACHE_VERIFY: cached stdlib interface for package `{name}` differs from a fresh derivation ({} vs {} bytes). The cached typed interface is a stale or incomplete substitute — please report this." thrown in BoundaryML/baml.

Solutions

1. Clear the stale cache (remove the cached bytecode artifacts or run with the cache disabled) and recompile so fresh stdlib interfaces are re-derived and re-cached
2. If the mismatch persists on a clean cache, report it to the BAML maintainers — the typed-interface derivation is nondeterministic or the cache key omits an input
3. Keep BAML_CACHE_VERIFY enabled in CI to catch stale cached export data early

When it happens

Trigger: Thrown at baml_language/crates/baml_cli/src/bytecode_cache.rs:309 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of BoundaryML/baml@bd85ce9dee (2026-09-12). Data as JSON: /api/errors/565c6022a01dbc87. Report an issue: GitHub.

Appendix: source

Thrown at baml_language/crates/baml_cli/src/bytecode_cache.rs:309

    /// Localized B-694 verify oracle (analog of `gocacheverify`): under
    /// `BAML_CACHE_VERIFY` the stdlib seed is *not* applied, so `db` derives every
    /// stdlib interface honestly; this compares that derivation byte-for-byte
    /// against any cached blob. A mismatch means the cached "export data" is a
    /// stale substitute that would change typecheck results — a hard error, and a
    /// tighter signal than the whole-`Program` byte-compare (it names the drifted
    /// package).
    pub(crate) fn verify_stdlib_interface(&self, db: &ProjectDatabase) -> anyhow::Result<()> {
        if !Self::verify_enabled() {
            return Ok(());
        }
        let Some(cached) = self.load_raw_stdlib_interface_for_verify() else {
            return Ok(());
        };
        let derived = extract_stdlib_interface(db);
        for (name, derived_bytes) in &derived {
            if let Some(cached_bytes) = cached.get(name) {
                if cached_bytes != derived_bytes {
                    anyhow::bail!(
                        "BAML_CACHE_VERIFY: cached stdlib interface for package `{name}` differs \
                         from a fresh derivation ({} vs {} bytes). The cached typed interface is a \
                         stale or incomplete substitute — please report this.",
                        cached_bytes.len(),
                        derived_bytes.len(),
                    );
                }
            }
        }
        Ok(())
    }

    /// Read the cached interface blob for the verify oracle, bypassing the
    /// `BAML_NO_STDLIB_INTERFACE_CACHE` disable (verify must still compare
    /// against whatever is on disk).
    fn load_raw_stdlib_interface_for_verify(
        &self,
    ) -> Option<std::collections::BTreeMap<String, Vec<u8>>> {

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