`IdentSlot` gains `expected_label()` and the round-trip
`from_expected_label()`. The four slot kinds map to the
user-facing labels "identifier" (NewName), "table name",
"column name", "relationship name".
`ident_ctx(slot)` now actually applies `slot.expected_label()`
as the chumsky label (was documentation-only after stage 6).
Parser errors and the hint panel's "expected: …" prose now
read with the slot-specific name: "expected table name"
instead of the generic "expected identifier". One parser
test updated accordingly; the four catalog `parse.token.*`
keys are unaffected (the slot labels are a parallel surface).
New `completion::SchemaCache { tables, columns,
relationships }` struct + `for_slot(slot) -> &[String]`
accessor. Empty by default; runtime wiring lands in a
follow-on substage. NewName slots return `&[]`
unconditionally.
`candidates_at_cursor` extended to accept `&SchemaCache`:
when the parser's expected-set includes a slot label,
schema candidates from the cache are added alongside the
keyword candidates. Both sources are then prefix-filtered,
combined, sorted, deduplicated. App::schema_cache field
threaded into both the App-side completion paths and the
ambient_hint computation in ui.
Tests: 738 passing, 0 failing, 1 ignored (730 baseline →
+8: 2 IdentSlot label round-trip tests, 6 completion-with-cache
cases covering table/column/relationship slots, prefix
filtering, empty cache, and NewName-no-candidates).
Clippy clean.
User-visible: identifier completion infrastructure is in
place but the cache is always empty — runtime wiring (the
next substage) will populate it on project load and after
successful DDL, at which point Tab on identifier slots
starts offering schema names.
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.
claude@clouddev1