fix: Fix DataCloneError from MCP grouped bar/pie query

[pulpdrew]

Summary

This PR fixes an error that occurred when querying pie/bar charts over metrics sources via MCP. Metrics sources errored when being cloned in the convertToCategorical function.

How to test on Vercel preview

Test locally by asking your agent to query bar/pie tile on a dashboard via MCP on a metrics source.

References

• Linear Issue:
• Related PRs:

[changeset-bot]

🦋 Changeset detected

Latest commit: 18cd601

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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[vercel]

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Project	Deployment	Actions	Updated (UTC)
hyperdx-oss	Ready	Preview, Comment	Jul 23, 2026 9:18pm
hyperdx-storybook	Ready	Preview, Comment	Jul 23, 2026 9:18pm

[github-actions]

🔵 Tier 2 — Low Risk

Small, isolated change with no API route or data model modifications.

Why this tier:

• Standard feature/fix — introduces new logic or modifies core functionality

Review process: AI review + quick human skim (target: 5–15 min). Reviewer validates AI assessment and checks for domain-specific concerns.
SLA: Resolve within 4 business hours.

Stats

• Production files changed: 1
• Production lines changed: 26 (+ 180 in test files, excluded from tier calculation)
• Branch: drew/fix-histogram-non-timeseries-display
• Author: pulpdrew

To override this classification, remove the review/tier-2 label and apply a different review/tier-* label. Manual overrides are preserved on subsequent pushes.

[greptile-apps]

Greptile Summary

Fixes MCP metric bar/pie tile queries by:

• Materializing hydrated Mongoose metricTables subdocuments into structured-cloneable plain objects.
• Adding integration coverage for grouped regular and exponential histogram bar charts.
• Adding a patch changeset for @hyperdx/api.

Confidence Score: 5/5

The PR appears safe to merge.

No blocking failures remain within the scope of the previous review thread.

Important Files Changed

Filename	Overview
packages/api/src/mcp/tools/query/helpers.ts	Converts metric table mappings to plain objects before categorical chart cloning and raw SQL source-field construction.
packages/api/src/mcp/tests/dashboards/queryTile.int.test.ts	Adds regression coverage for grouped regular and exponential histogram metric bar tiles queried through MCP.
.changeset/mcp-query-tile-metric-categorical-clone.md	Records the MCP categorical metric query fix as an API patch release.

_{Reviews (2): Last reviewed commit: "fix: Fix DataCloneError from MCP grouped..." | Re-trigger Greptile}

[greptile-apps]

Unsupported histogram aggregations exposed

When a user selects an exponential-histogram metric while the series uses avg, sum, min, max, count_distinct, any, or a custom aggregation, the editor preserves that unsupported aggregation and the query renderer throws instead of returning chart data.

Knowledge Base Used:

• App Components and Charts
• common-utils

[pulpdrew]

This comment was originally on code that was removed after rebase. This feature is enabled now.

[github-actions]

E2E Test Results

✅ All tests passed • 243 passed • 1 skipped • 991s

Status	Count
✅ Passed	243
❌ Failed	0
⚠️ Flaky	0
⏭️ Skipped	1

Tests ran across 4 shards in parallel.

View full report →

[github-actions]

Deep Review

✅ No critical issues found. The fix is correct and complete: metricTables is a nested Mongoose sub-schema declared with { _id: false } whose fields are all String, so toPlainMetricTables() → .toObject() yields a fully structured-cloneable plain object with no residual ObjectId, resolving the DataCloneError thrown by structuredClone inside convertToCategoricalChartConfig for pie/bar metric tiles. Both call sites (builder path and raw-SQL path) are covered, and the == null / 'toObject' in x guards are safe for already-plain inputs.

🟡 P2 — recommended

• packages/api/src/mcp/tools/query/helpers.ts:387 — The regression this PR fixes has no automated test: toPlainMetricTables is unexported, runConfigTile is never invoked by any test, and the convertToCategoricalChartConfig unit tests only pass plain object literals, so the metric + pie/bar clone path can silently break again.
  • Fix: Add a test that feeds a non-plain (Mongoose-like, .toObject()-bearing) metricTables through the categorical config path — or an integration test through runConfigTile with a metric source and displayType pie/bar — asserting it does not throw and yields a plain object.

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Reviewers (3): correctness, testing, maintainability.

Testing gaps: No regression test guards the fixed DataCloneError path (metric source + pie/bar via MCP). This review ran in a degraded environment (Bash and WebFetch unavailable); the change was reconstructed and verified from the repository working tree at HEAD (18cd6012) rather than from a raw git diff, so confidence rests on direct source inspection of the affected files and their dependencies.