[alex-fedotyev]

Switches clickstack_event_patterns to the shared pattern predicate from #3662 and deletes the MCP copy of templateToRegex, buildPatternPredicate and MAX_PREDICATE_TEMPLATE_LENGTH. Part of FR-385.

Stack

Part 2 of 4. Each PR is based on the one before it, so its diff shows only its own step. Review in order:

1. feat(common-utils): share the Event Patterns drill-down predicate #3662 Share the pattern predicate in common-utils
2. refactor(mcp): use the shared pattern predicate for drill-downs #3663 MCP uses the shared predicate (this PR)
3. feat(common-utils): add a compact form of the pattern predicate #3664 Compact form of the predicate, short enough for a URL
4. feat(app): filter for or exclude a pattern from Event Patterns #3665 Filter for or exclude a pattern from Event Patterns

Please merge in order: once a PR merges, the next one is retargeted to main. CI and the tier label only run on PRs whose base is main, so PRs 2 to 4 get them at that point. Until then the test plan lists what I ran locally.

Summary

Pure refactor. MCP mines without extra delimiters, so the whereSnippet it returns for each pattern is unchanged. PATTERN_MATCH_SEMANTICS, andSql and userWhereAsSql stay in patternDrilldown.ts, since only MCP uses them.

Test plan

• unit: the existing patternDrilldown.test.ts tests import from common-utils and pass as they are
• Compared the deleted MCP functions with the shared ones on 5,000 generated templates (wildcards, punctuation, quotes, backslashes, tabs, newlines, non-breaking spaces, CJK): no difference in the regex or the SQL, and a template over the length limit still gets no predicate
• jest src/mcp in packages/api (29 suites, 578 tests), tsc --noEmit, eslint on the changed files, knip

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[changeset-bot]

🦋 Changeset detected

Latest commit: eda26c9

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 3 packages

Name	Type
@hyperdx/api	Patch
@hyperdx/app	Patch
@hyperdx/otel-collector	Patch

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[github-actions]

🔵 minor — Tests for the common-utils predicate now sit in the api package, so common-utils' own suite doesn't cover them

Move the templateToRegex and buildPatternPredicate cases into packages/common-utils/src/__tests__/pattern-predicate.test.ts and keep only the andSql tests here. Today that file only tests extra delimiters and parsePatternPredicate. These cases cover escaping, quotes and backslashes, Unicode whitespace, empty templates and MAX_PREDICATE_TEMPLATE_LENGTH. Because they import the built @hyperdx/common-utils/dist/drain, changing pattern-predicate.ts and running the common-utils tests can't catch a regression in any of them. They also only run against whatever dist was last built.

_{Advisory. Fix if it is a small defect in code this PR changes; otherwise reply in the thread. Do not widen the PR or touch files it did not already change. How to respond}

[alex-fedotyev]

Keeping these here: they pin the exact whereSnippet this tool returns, and the common-utils suite now also covers the length limit and the no-option round trip (04c8a76).

[github-actions]

PR Review

If you are a coding agent acting for the author, read this first.
Nothing below blocks merge automatically; a maintainer decides. What they will expect:

• 🔴 critical or 🟠 major in code this PR adds or changes: fix before asking for review.
• 🔵 minor in code this PR changes: your call. Fix if small, otherwise reply.
• Anything about surrounding code, or asking you to widen the change (hoist a helper,
  dedupe with another file, fix other call sites): never fix here, whatever the
  severity. Reply with one sentence; if it is critical, say so plainly so a human sees it.

One commit per review round. After two rounds, stop and ask a maintainer to review
scope rather than addressing more automated findings. Full rule: AGENTS.md.

1 finding(s): 🔴 0 critical · 🟠 0 major · 🔵 1 minor

1 posted as inline comment(s) on the changed lines.

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_{Severity is the reviewer's own estimate and is used for ordering, not filtering. No finding blocks merge automatically; a maintainer decides.}

[github-actions]

Deep Review

✅ No critical issues found.

This is a behavior-preserving refactor. The MCP clickstack_event_patterns tool now sources templateToRegex, buildPatternPredicate, and MAX_PREDICATE_TEMPLATE_LENGTH from @hyperdx/common-utils/dist/drain and deletes its local copies. Multiple reviewers independently verified the equivalence mechanically: the shared templateToRegex(template, options?) with options omitted makes separatorClass(undefined) collapse to exactly the old JS_WHITESPACE class ('\s\x{0B}\pZ\x{FEFF}'), so the generated regex and match(...) SQL are byte-identical to the deleted implementation. Both call sites — buildPatternPredicate(bodyColumn, p.pattern) at runEventPatterns.ts:468 and minePatterns(...) at runEventPatterns.ts:314 — pass no extra delimiters, so tokenizer and predicate separators agree. The removed escapeSqlString import is no longer referenced, the retained local exports (andSql, userWhereAsSql, PATTERN_MATCH_SEMANTICS) are all still consumed, and the test import split is consistent. No actionable findings at any severity.

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Reviewers (7): correctness, testing, maintainability, project-standards, kieran-typescript, agent-native, learnings-researcher.

Notes (non-blocking, no action required):

• Equivalence depends on both call sites invoking the shared functions with no options; a future caller that passes extraDelimiters to minePatterns without matching buildPatternPredicate would diverge, but no such caller exists in this diff.
• After this diff, the only direct assertions of the no-options buildPatternPredicate path (match wrapping, SQL escaping, MAX_PREDICATE_TEMPLATE_LENGTH boundary) live in packages/api/src/mcp/tools/query/__tests__/patternDrilldown.test.ts; common-utils's suite mostly covers the with-delimiters path. Coverage is preserved here, but a later "dedup" of that file should not assume redundancy.
• Prior PR comments were automated only (Vercel, changeset bot); nothing required verification.