A zero encode() count does not, by itself, identify a bug. The write path may call a different method, expect vectors you already provide, use another embedder instance, or skip the input. First confirm the exact package and version, then trace one non-empty write from its entry point to the index upsert.
Why the method name matters
An embedder and a vector index have separate responsibilities in the documented Agent Development Kit (ADK) memory design: the embedder turns text into vectors, while the index stores vectors and finds nearby matches. The ADK documents an Embedder interface with an embed(input, options) method—not encode()—and a VectorIndex contract with an upsert method. Its example configures memory with both a model and an index, and also describes injecting a custom embedder. Read the ADK memory documentation.
That is one library’s contract, not a diagnosis of an unidentified application. Other libraries use different names and write semantics. For example, DF Embedder documents index_table as embedding an Arrow table and writing it as a Lance table, while embed_string exposes its embedding function directly. See DF Embedder’s README. Other surfaced APIs include a Rust encode method and a Go interface using Embed/EmbedOne; neither establishes what your write method does. These distinct API examples illustrate why the package must be identified.
Trace one write through the actual call path
- Identify the stack. Record the package and version, the exact object attached as the embedder, and the write method you call. Check that package version’s documented interface to see whether the expected method is
encode,embed, or something else. - Check the write contract. Inspect the method signature and implementation. Determine whether it accepts source text and embeds it internally, expects precomputed vectors from the caller, or delegates embedding to another component. A method that accepts vectors need not call a text embedder.
- Instrument the same object the write uses. Send one non-empty input and log entry into the write method, the number of texts received, entry into the documented embedder method, and the index
upsert. A counter attached to a different instance—or watchingencode()when dispatch uses another method—can remain at zero even when another part of the path is active. - Inspect skip and alternate paths. Verify whether the input is empty, already contains vectors, is deduplicated or filtered, or is handled by a different configured embedder. Check whether your call uses a separate batch or asynchronous entry point. These are possibilities to test in your implementation, not established causes of the symptom.
- Compare with a minimal supported example. Use the package’s documented write flow and supported embedder interface. At the index boundary, verify both the number of vectors and their dimensions; a successful write call alone does not establish that embedding happened as expected.
What to capture before diagnosing the cause
- Package/framework name and exact version.
- The write method and its input shape: text, records containing text, or precomputed vectors.
- The embedder interface method documented for that version, and the identity of the instance actually passed into the write path.
- Input count and whether the single test input is non-empty.
- Logs or breakpoints at write entry, embedder dispatch, and index upsert.
- Vector count and dimensions observed at the index boundary.
Until those details are known, “zero encode() calls” is an observation, not a root-cause diagnosis. The available evidence does not identify your package, write method, or implementation, so it cannot establish which branch explains the count.
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