Merge pull request 'ingest: unify transduce_prose/transduce_structured into one transduce()' (#117) from feat/transduce-unify into dev

lang/runtime/el_runtime.h

@@ -235,6 +235,20 @@ el_val_t  fs_list(el_val_t path);
 el_val_t  fs_exists(el_val_t path);
 el_val_t  fs_mkdir(el_val_t path);   /* mkdir -p, mode 0755                */
 
+/* Real on-disk byte count via stat() — not strlen(). Use this (not
+ * str_len(fs_read(path))) when a file may contain binary content, since
+ * fs_read()'s result truncates at the first embedded NUL under strlen-based
+ * string ops. Returns -1 if the path doesn't exist. */
+el_val_t  fs_size(el_val_t path);
+
+/* Binary-safe windowed read: read up to `length` bytes starting at byte
+ * `offset` from `path` and return them base64-encoded. Bytes are read and
+ * encoded in C without ever passing through an el_val_t string as raw
+ * bytes, so embedded NULs (routine in PCM audio) can't truncate the result.
+ * Returns "" on any failure or when offset is past EOF; a final short
+ * window returns only the bytes that actually exist on disk. */
+el_val_t  fs_read_b64_chunk(el_val_t path, el_val_t offset, el_val_t length);
+
 /* Length-explicit binary write. `length` is an Int (el_val_t holding the
  * byte count). The caller knows the length from context — typically because
  * `bytes` came from base64_decode (which produces a magic-tagged binary