fix(workflows): variable-scan metric cardinality, timing, and bytecode skip - #71500
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…e skip Review follow-ups on the variable-miss tracing: - Drop the hog_flow_id label from the miss counter: one series per workflow UUID is unbounded cardinality for a metric whose job is the fleet-wide rate (it sizes the publish-time lint work). The per-flow drill-down lives in the structured warn log, which already carries team, flow, action, and the missing names. - Time the scan with a histogram: it runs on every fresh entry into a function step, so its cost has to be observable rather than assumed. - Stop traversing bytecode/transpiled keys. They are the bulkiest part of a config and, contrary to the previous comment, not match-proof: a template string embedded verbatim as a bytecode constant matches the regex while the executor never renders from it - a latent false positive, covered by a new test row. Generated-By: PostHog Code Task-Id: 7f5083cf-5d17-4f37-8bee-8c43db70cb79
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Reviews (1): Last reviewed commit: "fix(workflows): variable-scan metric car..." | Re-trigger Greptile |
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meikelmosby
approved these changes
Jul 16, 2026
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Problem
Review follow-ups on #71060 (variable-miss tracing), raised in the team Slack thread after it auto-merged:
hog_flow_id- one Prometheus series per workflow UUID that ever misses a variable, unbounded cardinality for a metric whose job is fleet-wide ("are misses common enough to justify the publish-time lint?").bytecodearrays. The in-code comment claimed that's safe because compiled references storevariablesand the key as separate constants - true for compiled references, but a template string embedded verbatim as a bytecode constant (or thetranspiledJS form) does match the regex while the executor never renders from it: wasted work on the bulkiest part of the config, plus a latent false-positive warning.Changes
cdp_hogflow_missing_variable_referenceis now unlabelled. The per-flow drill-down lives in the structured warn log, which already carries team, flow, action, and the missing names - strictly richer than the label was. The metric is a day old, so nothing charts by the old label yet.cdp_hogflow_variable_scan_duration_secondshistogram around the scan (fixed buckets, 0.5ms-500ms). If it flatlines sub-millisecond we can delete it later with evidence in hand.bytecodeandtranspiledkeys, with the comment corrected to explain the false-positive case rather than asserting safety.How did you test this code?
Extended the existing parameterized suite with a row where a matching-looking template string sits inside a bytecode constant and a
transpiledstring - it must not be reported (catches anyone removing the skip and reintroducing the false positive; the pre-existing bytecode row only covered the compiled-reference shape that can't match). Fullhogflow-variable-usage+hog_functionsuites pass (28 tests), lint and tsc clean.Automatic notifications
Docs update
Not needed - internal observability only.
🤖 Agent context
Autonomy: Human-driven (agent-assisted)
Authored with PostHog Code (Claude), addressing colleague review feedback relayed from Slack. Skills invoked:
/writing-tests. The bytecode-skip finding turned out to be a correctness fix, not just perf - the original safety comment held for compiled references but not for template strings carried verbatim as constants.Created with PostHog Code