claude@clouddev1
06e8d1e769
Per the user's framing decision: there is no "completion
mode." Tab is just an action that consumes whatever is
expected at the cursor, and the existing always-on hint
panel (stage 5) tells the user what's available.
New `completion` module: `candidates_at_cursor(input,
cursor)` returns a `Completion { replaced_range,
partial_prefix, candidates }` based on the parser's
expected-token set at the cursor position. Filters to bare
keyword candidates only (no punctuation, no descriptive
labels), narrowed by the typed prefix (case-insensitive).
`LastCompletion` memo struct on `App::last_completion`
carries the cycle state: inserted_range, original_text,
candidates, selection_idx. Wrap-around forward/backward
indices.
App key handling (added before the existing matcher):
- Tab → cycle forward if memo present; else insert first
candidate; create / advance memo.
- Shift-Tab → cycle backward if memo present; else
insert last candidate (alphabetically) so the user can
jump to the end without cycling through everything.
- Esc / Backspace while memo alive → restore
original_text in inserted_range, place cursor at the
pre-Tab position, clear memo.
- Any other key → clear memo, then process normally.
The user's symmetry preference was load-bearing here:
"insert with one keystroke, remove with one keystroke."
Both Esc and Backspace honour that — multiple Tab cycles
collapse into one undo. Documented inline.
A single-candidate completion still creates a memo so
Esc/Backspace can undo it. Multiple Tabs in a row cycle
through the candidate list with wrap-around at both ends
(per the user's #2).
Tests: 728 passing, 0 failing, 1 ignored (705 baseline →
+23: 13 completion module + 10 app integration tests
covering Tab, Shift-Tab, cycling, wrap-around, Esc-undo,
Backspace-undo, multi-Tab-then-Esc, memo invalidation by
typing or cursor movement). Clippy clean.
Stage 8b will add multi-candidate hint-panel rendering
with scroll markers (`<` `>`) per the user's #2. Stage 8c
will plumb in identifier completion + invalid-identifier
detection.