otel: fix typeperf scrape mangled by cmd.exe quoting

[nficano]

xpc otel export scraped host CPU/mem with a quoted typeperf counter path run through the agent's cmd.exe /c shell. cmd.exe mangles the % and spaces in \Processor(_Total)\% Processor Time, so typeperf receives it truncated at \%, reports No valid counters, and exits 0xF0000002 (4026531842). Every scrape failed → the VM was marked unreachable and no metrics were emitted (this showed up as ~5.9k ERROR logs/day in SigNoz from xpc-otel on mon-01).

The perf counters themselves are healthy (typeperf -q Processor lists them). Fix: run typeperf with an explicit argv via the python subprocess passthrough (buildSubprocessPy, shell=False) instead of cmd.exe — the same command-line quoting workaround already used for reg.exe in runRegPassthrough.

Verified against the live VM: returns valid PDH-CSV % Processor Time and Available Bytes.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes
  • Enhanced remote performance counter collection by improving command execution. The system now correctly handles counter paths containing special characters (% and spaces), preventing collection failures and data truncation, and ensuring reliable performance monitoring across all remote systems.

[coderabbitai]

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 8edde13a-d4d1-4d74-9055-21f4be820028

📥 Commits

Reviewing files that changed from the base of the PR and between abf302f and daeeb0f.

📒 Files selected for processing (2)

• internal/cli/otel.go
• internal/otel/provider.go

📝 Walkthrough

Walkthrough

The PR refactors the scrapeTypeperf function in internal/cli/otel.go to invoke typeperf via Python subprocess with explicit argv passthrough (shell=False) instead of a cmd-shell command string, with added comments explaining the prior quoting issues with counter paths containing % and spaces.

Changes

Typeperf subprocess execution refactor

Layer / File(s)	Summary
Typeperf subprocess argv passthrough internal/cli/otel.go	The remote typeperf invocation is changed from runRemoteCmd(..., cmdLine, "cmd") to runRemoteCmd(..., py, "python") using buildSubprocessPy(...) for explicit argv passthrough. Inline comments document the prior cmd.exe quoting issue with % and spaces in counter paths, and how argv passthrough prevents counter-path truncation/mangling.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Poem

🐰 A shell once mangled paths with care,
Percent signs tangled in the air,
But Python's argv saves the day,
No more quoting leads astray!
Direct and true, the counters fly,
Typeperf runs, no more dry!

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and specifically summarizes the main change: fixing a typeperf issue caused by cmd.exe quoting that was mangling counter paths. It directly corresponds to the changeset's primary objective.
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.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/otel-typeperf-cmd-quoting

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