feat(starry): add syscall and qperf harness

.claude/skills/starry-syscall-harness/SKILL.md

@@ -0,0 +1,68 @@
+---
+name: starry-syscall-harness
+description: Audit and fix StarryOS syscall Linux-compatibility and qperf performance issues using the project harness. Use when comparing StarryOS syscall behavior with Linux, profiling StarryOS with qperf, running or extending tools/starry-syscall-harness, invoking its MCP tools, or validating syscall/performance fixes before opening a PR.
+---
+
+# Starry Syscall Harness
+
+Use this skill for StarryOS syscall semantic audits, qperf hotspot analysis, and fixes.
+
+## Core Rules
+
+- Run all StarryOS build, rootfs, QEMU, syscall probe, and qperf profile execution through Docker.
+- Use the configured image by default: `ghcr.io/rcore-os/tgoskits-container:latest`.
+- Prefer the harness entrypoint over hand-built commands:
+  `python3 tools/starry-syscall-harness/harness.py discover --arch riscv64`
+- Prefer the qperf harness entrypoint for performance work:
+  `python3 tools/starry-syscall-harness/harness.py perf-profile --arch riscv64 --timeout 20`
+- Treat host Linux probe output as the reference unless a case is explicitly documented as architecture-specific.
+- Treat qperf top functions, folded stacks, and generated fix candidates as triage inputs; confirm suspected bottlenecks in code before patching.
+- Keep fixes in the relevant syscall implementation; do not weaken probes to hide mismatches.
+- After changing StarryOS logic, run `cargo fmt` and targeted clippy in Docker:
+  `docker run --rm -v "$PWD":/work -w /work ghcr.io/rcore-os/tgoskits-container:latest bash -lc 'cargo xtask clippy --package starry-kernel'`
+
+## Workflow
+
+1. Run `python3 tools/starry-syscall-harness/harness.py doctor` to verify Docker and required tools.
+2. Run `python3 tools/starry-syscall-harness/harness.py discover --arch riscv64`.
+3. Read the JSON report under `target/starry-syscall-harness/<arch>/latest/report.json`.
+4. Fix only mismatches with clear Linux semantics.
+5. Rerun the harness for the affected arch, then run Docker clippy for changed crates.
+6. Before PR work, fetch upstream and create a clean branch from the target upstream branch.
+
+## Performance Workflow
+
+1. Run `python3 tools/starry-syscall-harness/harness.py perf-profile --arch riscv64 --timeout 20`.
+2. Read `target/starry-syscall-harness/perf/<arch>/latest/report.json` and `report.md`.
+3. Inspect `hotspots.top_functions`, `fix_candidates`, and `qperf/stack.folded`.
+4. If comparing optimization attempts, run `perf-diff --baseline <old-dir> --compare <new-dir>`.
+5. Use the default release profile for performance comparisons; pass `--debug` only when symbol detail is more important than optimized runtime behavior.
+6. Keep the default broad qperf sampling unless the report is dominated by non-kernel addresses; use `--kernel-filter` only after confirming the detected `.text` range matches QEMU callback addresses.
+7. Fix only bottlenecks supported by samples and code inspection.
+8. Rerun `perf-profile`, then run Docker clippy for changed crates.
+
+## MCP
+
+The MCP server is `tools/starry-syscall-harness/mcp_server.py`.
+
+Register it locally with:
+
+```bash
+codex mcp add starry-syscall-harness -- python3 /path/to/tgoskits/tools/starry-syscall-harness/mcp_server.py --repo /path/to/tgoskits
+```
+
+Available tools:
+
+- `starry_syscall_doctor`: checks Docker, image, and required toolchain availability.
+- `starry_syscall_discover`: runs Linux-vs-StarryOS syscall probes and returns the report.
+- `starry_perf_profile`: runs qperf in Docker, emits JSON/Markdown/CSV hotspot reports, and lists fix candidates.
+- `starry_perf_diff`: compares two qperf folded-stack outputs or profile directories.
+
+## Probe Changes
+
+When adding a probe:
+
+- Put deterministic C cases in `tools/starry-syscall-harness/probes/syscall_probe.c`.
+- Print one `CASE <name> key=value ...` line per syscall behavior.
+- Avoid fd numbers, timestamps, paths, pointer values, and scheduler-sensitive output in comparisons.
+- Prefer small syscall-focused probes that can run under BusyBox init without extra packages.

AGENTS.md

@@ -18,6 +18,8 @@
 - Use `board-uboot-fsck-repair` when a physical board Linux rootfs needs ext4 recovery through U-Boot, initramfs fsck reports unrepaired corruption, OrangePi-5-Plus needs `extraboardargs=fsckfix`, or Starry board write tests must be bracketed by Linux fsck/boot checks.
 - `crates-io-owner`: project-local skill at `.claude/skills/crates-io-owner/SKILL.md`
 - Use `crates-io-owner` when the user wants to add or verify `github:rcore-os:crates-io` for branch-added crates, asks which new crates still need the crates.io team owner, or explicitly wants `cargo owner` used instead of `Cargo.toml` metadata.
+- `starry-syscall-harness`: project-local skill at `.claude/skills/starry-syscall-harness/SKILL.md`
+- Use `starry-syscall-harness` when auditing StarryOS syscall Linux-compatibility semantics, running syscall differential tests, running qperf-based StarryOS performance profiling, using its MCP tools, or preparing fixes from harness output.
 
 ## Other Requirements