pc index vector query: empty --namespace coerced to __default__

[matthewwalk]

Background Info

• OS: macOS (Darwin 25.x)
• Browser: N/A (CLI-only; no browser involved)
• CLI Version: 0.4.5 (output of pc version)
• How did you install the CLI? Homebrew

Reproduction steps

Steps:

1. Confirm the index has vectors under the empty-string namespace, e.g. pc index stats --index-name <index-name> shows a "" key in namespaces with a non-zero vector_count.
2. Save a query vector as a JSON file containing only a JSON array of floats (e.g. vec.json with [0.1, 0.2, ...]).
3. Authenticate with pc (e.g. browser login / user token) and set project context with pc target as usual.
4. Run:

pc index vector query \
  --index-name <index-name> \
  --namespace "" \
  --vector vec.json \
  --top-k 5 \
  --include-metadata \
  --json

5. Observe the CLI output: it reports Namespace: __default__ (human table) or JSON containing "namespace":"__default__", with no matches (or an empty table), even though stats show vectors under "".

Expected behavior

The query should target namespace "", consistent with Pinecone REST POST https://<index-host>/query when the request body includes "namespace": "".

Screenshots

CLI output is effectively only {"namespace":"__default__"} with no useful matches, or the human-readable table shows Namespace: __default__ with no rows, while pc index stats still shows all vectors under the "" namespace key.

Additional context

Add any other context about the problem here.

• Actual vs REST: The same query vector sent via REST POST /query with "namespace": "" returns expected neighbours; the issue appears specific to how the CLI passes or defaults --namespace.
• Hypothesis: Empty --namespace may be treated as unset and fall back to __default__, rather than being sent as an explicit empty string.
• Workaround: Use the data-plane REST POST https://<index-host>/query with "namespace": "" in the JSON body until CLI behaviour matches.

[austin-denoble]

Hey @matthewwalk, thanks for reporting. You're correct in that the CLI falls back to using "default" as the empty namespace value.

However, I'm confused as to how you're seeing the empty "" namespace on response from pc index stats. The API version that v0.4.5 is tied to should return "default" for this case, so I'm not sure how you're seeing what you're seeing.

I have a PR up to remove the explicit coercion in the CLI, but I'd like to understand how you got into this state in the first place.