Control semantic costs

Use this workflow before running semantic queries on a paid backend.

1. Estimate calls with --explain

Run the query with representative input and --explain:

printf '[{"msg":"urgent"},{"msg":"other"}]' \
  | ajq --explain '.[] | select(.msg =~ "urgent") | .msg'

Read post_dedup_judgements in the estimate block:

estimates:
  estimate_status: available
  static_call_sites: 1
  input_frames: 1
  harvested_judgements: 2
  post_dedup_judgements: 2

That number is the count to budget against. Repeated values are deduplicated before the backend is called.

2. Add a hard cap with --max-calls

Set the cap at or below your budget. ajq aborts before issuing the call that would cross it:

printf '[{"msg":"urgent"},{"msg":"other"}]' \
  | ajq --backend mock --max-calls 1 '.[] | select(.msg =~ "urgent") | .msg'

With two distinct judgements and a cap of one, the run fails safely:

ajq: error: query ".[] | select(.msg =~ \"urgent\") | .msg" runtime error in frame 1: max calls cap exceeded: cap 1, run needs 2 post-dedup backend judgements; aborting before issuing backend call 2.

Paid backends (anthropic, openai, and openrouter) default to --max-calls 100. Use --max-calls 0 only when you intentionally want no cap. --backend-concurrency changes only how many requests from an already-approved batch can be in flight; it does not change this count or reserve extra calls. Keep paid providers at the sequential default of 1 while establishing a rate-limit budget, then use at most 2 only if the provider’s account limits and retry capacity allow it.

3. Inspect a successful run with --stats

After choosing a cap, run with --stats to print a summary to standard error:

printf '[{"msg":"urgent"},{"msg":"urgent"},{"msg":"other"}]' \
  | ajq --backend mock --stats '.[] | select(.msg =~ "urgent") | .msg'

The data still goes to standard output:

"urgent"
"urgent"

The stats show harvested work, post-dedup backend calls, cache hits, and elapsed time:

ajq stats:
  input_frames: 1
  semantic_call_sites: 1
  harvested_judgements: 3
  post_dedup_backend_calls: 2
  cache_hits: 0
  elapsed: ...

For paid models in ajq’s pricing table, stats also include an estimated USD cost. Treat it as a budgeting estimate, not a provider bill.

Related

• --explain output reference — every estimate field.
• Backends reference — which backends have a paid default cap.
• Manage the judgement cache — reduce repeat backend calls.