Phase 3 Plan F: editor + persistence + final demo (Phase 3 complete)#18
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8 tasks: edit binary skeleton + raw mode (1), file load + ^S save (2), insert + backspace (3), horizontal arrows + ANSI redraw (4), vertical arrows (5), e2e-editor (6), e2e-persist (7), trace polish + README + deck updates (8). Closes Phase 3.
edit.zig is a stub today: enter raw mode, read bytes, exit on ^X, restore cooked mode. No file load, no save, no rendering yet — but it proves the raw-mode in/out dance works end-to-end against the 3.E console line discipline.
edit /etc/motd now loads the file into content[0..content_len] before entering raw mode, and ^S re-opens the path with O_WRONLY|O_TRUNC| O_CREAT and writes the buffer back. With no insert/delete logic yet, ^S^X is a no-op round-trip that leaves the file byte-identical.
Printable bytes (and \n / \r normalized to \n) insert at the cursor offset, shifting the tail right and bumping cursor. Backspace shifts the tail left, decrementing cursor. Buffer-full inserts drop silently; backspace at offset 0 is a no-op. Cursor still moves only via insert (no arrow keys yet — Tasks 4-5).
A 2-state ESC parser ingests ESC [ A/B/C/D. This task wires C (right) and D (left); A/B are accepted but no-op until Task 5. After every content/cursor mutation, redraw() emits \x1b[2J\x1b[H to clear, prints the full buffer, then \x1b[<row>;<col>H to land the terminal cursor at the byte-offset's row/col — both 1-based per ANSI semantics. Row/col arithmetic walks newlines from the start of the buffer.
ESC [ A and ESC [ B move the cursor to the same column on the previous/next row, clamping to the target line's length. lineStart and lineEnd walk newlines forward/backward from a given offset. The motd demo is one line so this is defensive plumbing, but it makes edit usable on multi-line files.
editor_input.txt is a 43-byte binary fixture that drives the canonical demo session: edit /etc/motd → 2× right-arrow → Y → ^S → ^X → cat /etc/motd → exit. The harness copies shell-fs.img to zig-out/ editor-test.img so the editor's save doesn't mutate the build artifact, spawns ccc with --input + --disk, captures stdout, and asserts the discriminating landmark "$ cat /etc/motd\nheYllo from phase 3\n" appears (proves the editor wrote the file and cat read it back through a fully-restored cooked-mode shell).
Two-pass test: pass 1 writes /etc/motd via "echo replaced > /etc/motd"; pass 2 (a fresh ccc invocation on the SAME --disk image) cats /etc/motd and the harness asserts "replaced\n" appears after the prompt. Proves the kernel's bwrite path actually mutates the host-backed block device file and that pass 2 reads it via a fresh kernel + bufcache instance — the only state surviving between passes is the on-disk image. Uses cooked-mode echo (independent of edit.zig) so persistence regressions can't be masked by editor regressions.
Bumped README to "Phase 3 complete" with a Plan 3.F summary block; added kernel-edit / e2e-editor / e2e-persist rows to the build commands table; added edit.zig + the new e2e fixtures to the layout. Deck: replaced the "Next · plan 3.f" panel with a ✓ 3.F status row matching the 3.A-3.E rows above; flipped "Phase 3 · underway" to "Phase 3 · complete" on the closing chapter; added a Ch 3.F slide. Trace eyeball pass over the editor session showed the existing markers are consistent end-to-end — no formatter changes needed.
Code review caught two issues in the index.html updates: 1. The new ✓ 3.F status row was placed AFTER </div> closing check-list, leaving it as a stray sibling of check-list inside two-col rather than as the 6th row alongside 3.A-3.E. Moved it inside check-list. 2. The new Ch 3.F slide used bare <code> tags in its body and caption instead of <code class="inline"> — inconsistent with every other slide's body text. Added the inline class to all 12 instances.
… column
Final-review nits caught two cosmetic issues:
1. zig fmt --check failed on src/kernel/user/edit.zig — the compact
"0x08, 0x7F => { backspace(); redraw(); }," switch arms got
expanded to multi-line by the formatter. Ran zig fmt to match the
neighbor files' style.
2. The epilogue's <div class="two-col"> kept "grid-template-columns:
1.25fr 1fr" even after the right-column "Next · plan 3.f" panel
was replaced by the in-checklist 3.F row. Collapsed to 1fr so the
reserved right column doesn't leave wasted whitespace.
Phase 3 spec §Definition of Done's "^C in the shell cancels a foreground program (proves kill-flag)" bullet had no automated test through Plan 3.F. The code path was fully wired (console.feedByte catches 0x03 → proc.kill(fg_pid) → killed flag set → console.read returns -1 → syscall dispatch calls proc.exit) but only verified by code inspection. This adds a 10-byte fixture "cat\n\x03exit\n" and a harness that asserts the landmark "cat\n^C\n$ exit" appears in stdout after the ccc run — proving cat actually got killed, the shell returned to its prompt loop, and exit cleaned up normally.
The e2e-cancel test added in commit ad65594 closes Phase 3 §DoD's "^C cancels foreground program" bullet, but the README's Plan 3.F summary block and the deck's ✓ 3.F row + Ch 3.F slide didn't yet mention it. This commit extends those doc surfaces so the kill-flag chain is documented alongside the editor and persistence stories.
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Summary
Closes Phase 3 — the multi-process OS phase. After this lands, the spec's full §Definition of Done holds end-to-end.
edituserland binary (src/kernel/user/edit.zig, ~205 LoC) — cursor-moving text editor that finally exercises 3.E's raw-mode console arm. Loads file into a 16 KB buffer; redraw-on-every-keystroke ANSI loop; ESC[A/B/C/Darrows, printable insert, backspace,^Ssave (close +O_TRUNCre-open),^Xexit (cooked-mode restore viadefer).e2e-editor(43-byte fixture: edit /etc/motd → 2× right → Y → ^S^X → cat assertsheYllo from phase 3);e2e-persist(two ccc passes on copied image; pass 2 sees pass 1's writes);e2e-cancel(10-byte fixturecat\n\x03exit\nproves the kill-flag chain end-to-end —console.feedByte(0x03)→proc.kill(fg_pid)→killedflag →console.readreturns -1 → syscall dispatch callsproc.exit).index.html) gets a Ch 3.F slide + ✓ 3.F status row replacing the prior "Next · plan 3.f" panel; closing chapter title flipped from "Phase 3 · underway" to "Phase 3 · complete".The plan doc lives at
docs/superpowers/plans/2026-04-27-phase3-plan-f-editor-persist.md(8 tasks, each landing as its own commit).Test plan
zig build test— all unit tests passzig build riscv-tests— rv32ui/um/ua/mi/si-p-*(67 tests) passe2e,e2e-mul,e2e-trap,e2e-hello-elfe2e-kernele2e-multiproc-stub,e2e-fork,e2e-fs,e2e-shelle2e-editor,e2e-persist,e2e-cancele2e-snake,e2e-plic-blockzig build run -- --disk shell-fs.img kernel-fs.elfboots to\$prompt;edit /etc/motdworks interactively;^Xreturns cleanly to cooked-mode shellPhase 3 §Definition of Done — closed
kernel.elfbuildskernel-fs.elf)mkfs+fs-imgproducefs.imgshell-fs.img)ccc --disk … kernel.elfboots /bin/init → /bin/sh →\$prompte2e-shelle2e-shell,e2e-editor,e2e-persist^Ccancels foreground programe2e-cancelriscv-testspasse2e-cancel)--traceshows PLIC--- interrupt 9 (supervisor external, src N) ---markers🤖 Generated with Claude Code