cleonos/docs/stage28.md

Stage 28 - ANSI TTY + Default User Shell Entry + User Syscall Trace

Goal

• Add ANSI color control support to TTY.
• Introduce ANSI-colored experience in user shell.
• Default to entering user shell after kernel is ready.
• Add serial log tracing for syscalls while user programs are running.

Implementation

• TTY:
  • Added ANSI CSI/SGR parsing (ESC[...m) for standard foreground/background colors.
  • Added support for reset/default color behavior (0, 39, 49) and bright color range (90..97, 100..107).
  • Added per-cell color buffers so scrolling/redraw keeps color attributes.
• User shell:
  • Colored prompt and startup text now use ANSI sequences.
  • Added ansi/color command to preview palette.
  • clear now uses ANSI clear/home sequence.
• Boot behavior:
  • Enabled user shell auto-exec by default in userland manager.
  • Boot log now reports default user-shell mode when auto-exec is enabled.
• Syscall tracing:
  • Added bounded debug trace in clks/kernel/syscall.c for syscalls issued while a user-path program is active.
  • Trace emits begin/end markers and syscall IDs with budget guard to avoid log flooding.

Acceptance Criteria

• User shell prompt/output can display ANSI colors correctly on TTY.
• Boot enters default user-shell flow (auto launch enabled).
• Serial logs include syscall trace lines while user programs execute.
• Stage27 and Stage28 docs are present and indexed in docs/README.md.

Build Targets

• make userapps
• make ramdisk
• make iso
• make run

QEMU Command

• make run

Debug Notes

• If ANSI text shows raw escape chars, verify clks/kernel/tty.c ANSI parser path is compiled.
• If user shell does not auto launch, check clks/kernel/userland.c auto-exec flags and retry tick flow.
• If syscall trace is missing, confirm clks_exec_current_path_is_user() is true during the target run.