`get_daily_spend_from_prometheus` was interpolating the `api_key`
query parameter into a PromQL `hashed_api_key="..."` label matcher
with an f-string. Any caller of `/global/spend/logs` could inject a
bare `"` to terminate the matcher and append arbitrary PromQL
operators or extra metric selectors, exfiltrating cross-tenant
telemetry from the connected Prometheus instance.
Replace the f-string with `_quote_promql_string_literal`, which uses
`json.dumps` to render a complete Go-compatible double-quoted literal.
PromQL string literals follow Go's escape rules per
https://prometheus.io/docs/prometheus/latest/querying/basics/, and
JSON's quoting is a strict subset, so the same escape covers
backslash, embedded quote, and control-character cases without rolling
a bespoke escape table.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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