feat: In-CLI performance monitoring dashboard (/perf command)

[1nonlyasta]

What would you like to be added?

An in-CLI performance monitoring dashboard accessible via a /perf slash command with subcommands:

• /perf — Session timing overview, memory summary, tool/API aggregate stats
• /perf memory — Detailed heap/RSS breakdown with utilization bars and warnings
• /perf tools — Per-tool execution table (calls, avg latency, success rate)
• /perf api — Per-model API latency and token usage breakdown
• /perf export — JSON performance report for CI integration or external analysis

The CLI already has a robust telemetry backend (memory monitor, startup profiler,
OpenTelemetry metrics in packages/core/src/telemetry/) but none of these insights
are surfaced to users. This feature bridges that gap using an Ink-based dashboard
component, following the same patterns as the existing /stats command.

Why is this needed?

1. Contributors can identify performance regressions during development without
   external profiling tools
2. Users get visibility into what's consuming time — API calls vs tool execution
3. CI integration potential for automated regression detection across releases
4. Complements the existing /stats command with performance-specific views
5. Aligns with GSoC 2026 Project Idea Configure linter + prettier. #5: "Performance Monitoring and Optimization Dashboard"

I have a working prototype ready and would love to contribute this as a Draft PR.
Happy to adjust the approach based on maintainer feedback.

Additional context

Technical approach follows existing patterns from statsCommand.ts and StatsDisplay.tsx.
Uses SessionMetrics from uiTelemetryService + process.memoryUsage() for real-time data.
New Ink component PerfDisplay.tsx with themed tabular output.

I have a working prototype and am happy to submit it as a Draft PR for review.

[gemini-cli]

Found possible duplicate issues:

• Feature: Add performance monitoring dashboard command (/perf) #22403

If you believe this is not a duplicate, please remove the status/possible-duplicate label.

[1nonlyasta]

Hi! I'm implementating this as part of GSoC 2026 Project Idea 5 (Performance Monitoring and Optimization Dashboard). I've already opened a working Draft PR for this here: #22485.

I wanted to create a separate issue to track the specific requirements for the GSoC proposal, but I'm happy to consolidate discussions here or in the related issue #21142 / #22403 if preferred by the maintainers!

[1nonlyasta]

/assign

[gemini-cli]

👋 @1nonlyasta, thanks for your interest in this issue! We're reserving self-assignment for issues that have been marked with the help wanted label. Feel free to check out our list of issues that need attention.

[cocosheng-g]

Triage Update

Reclassifying this feature request. Because a performance monitoring dashboard deeply touches core telemetry, API usage statistics, and internal performance tracking mechanisms, it requires significant maintainer oversight and architectural alignment. As such, it is not currently categorized as a Help-wanted issue.

[Adib234]

Thank you for bringing this to our attention. Right now, our engineering team is focusing all resources on critical system maintenance and core stability. Because of this, we don't have immediate plans to address this specific issue, but we truly appreciate you flagging it for us.