fix(querier): let the MCP query_logs tool run count aggregations

[jensholdgaard]

Let the MCP query_logs tool run count aggregations

The MCP query_logs handler unconditionally injected its row-cap limit stage (mcp.rs), but count [by …] and limit are mutually exclusive (compile::validate, RFC 0002 amendment 2026-07-15). So every aggregation submitted through the MCP surface was rejected with "a query with a count stage does not support limit" — an agent could page raw rows but couldn't ask count by attr.model about its own data.

The JSON /v1/query path already handles this correctly: handle_query computes is_aggregation and skips apply_limit for count queries (querier.rs:481). This mirrors that guard into the MCP handler, so the two surfaces behave identically.

Change

• mcp.rs: skip the injected limit cap when the statement carries a Stage::Count — same guard as the JSON API, referenced in the comment.

Test (RFC 0027 §5, regression)

• rfc0027_3_query_logs_count_aggregation: runs template_id == 1 | count by template_id through the full MCP protocol with a non-null limit argument set — proving the cap is ignored for aggregations rather than injected — and asserts the tool's answer is byte-identical to the JSON API's for the same statement.

Invariants

No hazard/pillar surface touched — this is a query-surface parity fix (hazard #6: the DSL layer must behave the same across surfaces). No schema, WAL, or miner change.

Verification

• cargo clippy -p ourios-server --all-targets --all-features -- -D warnings → clean
• cargo test -p ourios-server --test it rfc0027 → 8 passed, 0 failed (incl. the new regression)
• cargo fmt --all --check → clean

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes
  • Fixed log queries using count by aggregations with a specified limit.
  • Aggregated queries now return grouped results instead of being rejected due to the limit setting.
  • Ensured results remain consistent between MCP and JSON API responses.

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Review details

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: a7d5346f-6db8-40ac-84d6-99a79e6f4a45

📥 Commits

Reviewing files that changed from the base of the PR and between c9c3fee and 6a89141.

📒 Files selected for processing (2)

• crates/ourios-server/src/mcp.rs
• crates/ourios-server/tests/it/rfc0027_mcp.rs

📝 Walkthrough

Walkthrough

The MCP query_logs tool now avoids applying its hard row limit to queries containing count aggregations. A regression test verifies grouped results and equivalence with the JSON API when a limit is supplied.

Changes

Count aggregation limit handling

Layer / File(s)	Summary
Skip row caps for count queries and validate the MCP response crates/ourios-server/src/mcp.rs, crates/ourios-server/tests/it/rfc0027_mcp.rs	query_logs detects Stage::Count before applying the limit cap, and the RFC0027.3 test verifies grouped aggregation output and JSON API equivalence.

Estimated code review effort: 2 (Simple) | ~10 minutes

Possibly related PRs

• jensholdgaard/ourios#414: Modifies MCP query_logs limit and hard-cap behavior.
• jensholdgaard/ourios#533: Changes count aggregation handling to avoid default limit clamping.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly states the main change: allowing MCP query_logs to run count aggregations.
Description check	✅ Passed	The description covers the summary, rationale, change, regression test, invariants, and verification, with only minor template deviations.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix-mcp-count-aggregation

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[Copilot]

Pull request overview

This pull request fixes a parity bug in the Ourios querier’s MCP query_logs tool: MCP previously always injected a row-cap limit, which made count [by …] aggregations fail validation because count and limit are mutually exclusive. The change mirrors the JSON API behavior by skipping apply_limit when the parsed statement includes a Stage::Count, and adds an integration regression test that exercises the full MCP protocol and asserts MCP/JSON output equivalence.

Changes:

• Update the MCP query_logs handler to detect Stage::Count and avoid injecting the row-cap limit for aggregations.
• Add an integration test that runs count by through MCP with a non-null limit argument and asserts the response matches the JSON API byte-for-byte.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
crates/ourios-server/src/mcp.rs	Skip MCP-injected limit when the query includes Stage::Count, matching the JSON API guard.
crates/ourios-server/tests/it/rfc0027_mcp.rs	Add regression test proving query_logs count aggregations work over MCP and match JSON API output.

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@crates/ourios-server/src/mcp.rs`:
- Around line 303-310: Add colocated unit tests in mcp.rs for the query-building
logic around is_aggregation and apply_limit, covering a normal row query, count,
and count by. Assert that limits are applied to row queries but omitted for both
aggregation forms, while preserving the existing integration regression test.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 9154a956-c27e-43a2-8231-7b8ea14a40bf

📥 Commits

Reviewing files that changed from the base of the PR and between c411840 and c9c3fee.

📒 Files selected for processing (2)

• crates/ourios-server/src/mcp.rs
• crates/ourios-server/tests/it/rfc0027_mcp.rs

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated no new comments.