# Session handoff — 2026-05-19 (19)

Nineteenth handover. A focused **implementation run** that
**finished ADR-0027**: the §4 "known follow-ups" from
handoff-18 are all done. ADR-0027's §2 always specified that
"highlighting and the hint panel read the individual
diagnostics" — handoff-18 shipped the indicator and the model
but left that wiring as a follow-up. It is now wired.

**Headline: the diagnostics are visible where they happen.**
An unknown table / column (ERROR) and a dubious comparison
(WARNING — type mismatch, `= NULL`, and now `LIKE` on a
numeric column) are overlaid on the input field *globally*
and explained in the hint panel — not just summarised by the
`[ERR]` / `[WRN]` indicator.

## State at handoff

**Branch:** `main`. Working tree clean. **7 commits** since
handoff-18 (`39b92a7`), all local — push asynchronously, not
blocking.

```
<this file>  docs: handoff 19 + ADR-0027 follow-up/amendment notes
c1c9f6c runtime: extract the indicator debounce into a tested state machine
400fb71 ui: surface diagnostics in the ambient hint panel (ADR-0027 §2)
bbfb70c ui: overlay diagnostic spans on the input field (ADR-0027 §2)
437b2f2 walker: flag LIKE on a numeric column (ADR-0027 Amendment 1)
3912fb5 walker: precise per-literal spans for expression WARNINGs
426e801 command: Operand carries a source span
```

**Tests:** **1125 passing, 0 failing, 1 ignored** (`cargo
test` — up from 1100 at handoff-18). The ignored test is the
long-standing `` ```ignore `` doc-test in
`src/friendly/mod.rs`. Typing-surface matrix: **161 cells**,
unchanged (one cell's *input* was corrected — see §3).

**Clippy:** clean (`cargo clippy --all-targets -- -D
warnings`, nursery group).

## §1. What this run did — the three §4 follow-ups

handoff-18 §4 listed three "known follow-ups (none blocking)".
The user reviewed them, judged §4-item-1 to be unfinished
ADR-0027 *scope* (the §2 Decision text, not an optional
extra), and asked for **all three** — including the small ADR
amendment item 3 needs. All three are done.

### Item 1 — diagnostic highlight + hint wiring

§2 of ADR-0027: the indicator is the *summary*; highlighting
and the hint panel carry the *where* and *why*. Built across
four commits:

- **`Operand` carries a source span** (`426e801`). Each
  WHERE-expression operand now records the byte range of the
  terminal it was built from. `Operand`'s `PartialEq` is
  hand-written to **ignore** the span — it is editor
  metadata — so `Command` equality stays whitespace- and
  position-independent and the large `Expr` test corpus
  needed no assertion changes.
- **Precise per-literal WARNING spans** (`3912fb5`). The old
  WARNING span was coarse — the whole WHERE clause.
  `predicate_warnings` now anchors each WARNING to exactly
  the offending literal operand; `where_clause_span` is
  gone.
- **Highlight overlay** (`bbfb70c`). `render_input_runs`
  overlays the walker's schema-aware diagnostics: ERROR in
  the error colour, WARNING in `theme.warning`. New
  `overlay_span` covers a token's whole byte range (the
  older `overlay_error` hit only the run at a single byte).
  The overlay is **global** — every flagged token is
  coloured wherever it sits, not just under the cursor,
  which is exactly the gap §Context described. The
  pre-existing cursor-local invalid-identifier overlay is
  kept (it covers in-progress idents, which produce no
  diagnostics); the two are additive and idempotent.
- **Hint panel** (`400fb71`). `ambient_hint` surfaces a
  diagnostic's message. `walker::input_diagnostics` is
  non-empty *only* for a command that structurally parses,
  so a non-empty result means "complete and submittable,
  but wrong" — checked early, ahead of slot hints and
  completions, so a flawed-but-parsing command no longer
  shows the misleading "Submit with Enter". The diagnostic
  under the cursor wins, else the most severe.

### Item 2 — debounce test coverage (`c1c9f6c`)

The indicator debounce was two locals in the event loop with
no unit coverage. The decision logic is now the
`IndicatorDebounce` state machine in `runtime` — `note_event`
/ `settle` / `is_armed` / `visible`, 7 unit tests for the
keystroke / settle cycle (including: a background event
mid-typing must not cancel the owed recompute). No behaviour
change; the `tokio` timer and terminal stay in the loop. A
PTY-tier test of the *actual timing* remains the one
integration-level gap (consistent with ADR-0008's four-tier
strategy).

### Item 3 — `LIKE` on a numeric column (`437b2f2`)

A genuinely new WARNING trigger, so it needed an ADR change:
**ADR-0027 Amendment 1**. `LIKE` is a text-pattern match;
against an `int` / `real` / `decimal` / `serial` column it
runs but is almost never intended. New `Type::is_numeric`,
catalog key `diagnostic.like_numeric`. Scope is deliberately
numeric-only — `bool` and the text-/blob-backed types are
not flagged; rationale is in the amendment. `docs/adr/
README.md` updated per the index-upkeep rule.

## §2. ⚠️ Two manual-testing bugs — NOT fixed, queued next

Mid-run the user reported two bugs from manual testing and
explicitly deferred the fixes. **These are the top of the
next session's queue.** They are unrelated to ADR-0027.

1. **`add 1:n relationship` — missing completion + wrong
   usage hint.** Typing `add 1:n relationship from
   Artists.album_id to Albums.id --` does **not** offer
   `--create-fk`. Separately, the ambient hint at the end of
   `add 1:n relationship from … to …` shows the **wrong**
   usage block — `add column …` — because
   `grammar::usage_key_for_input` (commit `151ed08`)
   disambiguates `add column` / `add index` but not the
   `1:n relationship` form, so it falls back to the first
   `add` form. Same *class* of bug `151ed08` fixed; the fix
   is to teach `usage_key_for_input` the relationship form,
   plus wire the `--create-fk` flag completion.
   *(The user confirmed the `[ERR]` shown for the
   non-existent column in that input is correct and welcome
   — that is this run's schema-existence diagnostic working.
   Do not touch it.)*
2. **`--resume` points at an unpersisted temp project.** An
   empty temp project is created on launch but, by design
   (ADR-0015), not persisted when it has no content — yet
   `last_project` still records its path, so a later
   `--resume` fails with a confusing "path does not exist".
   The user asked for: (a) `last_project` updated only once
   a path is **truly persisted with content**; (b) a
   friendly error when `--resume` finds no `last_project`
   at all.

Both are recorded as tasks (#7, #8 in this session's task
list) with full repro detail.

## §3. Architectural delta (vs. handoff-18)

### Command AST

- `Operand` is now a struct-variant enum —
  `Column { name, span }` / `Literal { value, span }` —
  carrying a byte `span`. **`PartialEq` is hand-written to
  ignore `span`** (see the type docs); `Eq` still derived.
  `Operand::span()` accessor; `Operand::NO_SPAN` for
  programmatically-built operands (`RowFilter::eq`).

### Walker

- `walker::input_diagnostics(source, schema) -> Vec<Diagnostic>`
  — the sibling of `input_verdict`; the shared entry point
  for the highlight overlay and the hint panel.
- `predicate_warnings` emits per-literal spans;
  `pair_type_mismatch` returns `(message, span)`;
  `where_clause_span` removed.
- `like_numeric_warning` — the `LIKE`-on-numeric WARNING
  (Amendment 1). `Predicate::Like` is no longer a no-op arm.

### ui / input_render

- `render_input_runs` overlays diagnostics (`overlay_span`,
  new). `ambient_hint` has a diagnostic branch right after
  the Tab-cycle memo; `pick_hint_diagnostic` chooses
  cursor-local, else most-severe.

### runtime

- `IndicatorDebounce` state machine replaces the
  `indicator_pending` local; `app.input_indicator` mirrors
  its `visible` for the renderer.

### Types / catalog

- `Type::is_numeric()`. New catalog key
  `diagnostic.like_numeric` (+ `friendly::keys` registry
  entry).

## §4. Docs touched

- **ADR-0027** — new "Follow-up" section (the §2 wiring
  completed) and "Amendment 1" (`LIKE` on a numeric column);
  the three stale "As-built notes" bullets updated to point
  at them.
- `docs/adr/README.md` — ADR-0027 line notes Amendment 1.
- `docs/requirements.md` — test baseline (→ 1125) and the
  `S6` entry note the completed wiring + amendment.

## §5. What's next

1. **The two §2 bugs** — `add 1:n relationship` completion /
   usage hint, and `--resume` / `last_project`. The user
   deferred these explicitly; they are first in line.
2. **ADR-0028 — query plans (`explain`).** Still the last
   unimplemented member of the handoff-16 design trio;
   **Accepted**, not started. `show data … where` is the
   filtered query whose plan flips between a full scan and
   an index search.

Other open clusters unchanged from handoff-16/17/18
(snapshot/undo `U`-series; constraints `C3`; `C4` m:n;
`C3a`; `C1` table rename; `H1`; `SD1`; `TT5` CI; `V4`; `I1`;
`TU1`). Prioritisation is a user product decision — ask.

## §6. How to take over

1. **Read this file, then handoff-18** (ADR-0026/0027
   implementation), then handoff-17 / handoff-16 as needed.
2. **Read `CLAUDE.md`** — working-style rules.
3. **Read `docs/adr/0027-input-validity-indicator.md`** —
   especially the new "Follow-up" and "Amendment 1"
   sections.
4. **Run `cargo test`** — 1125 passing, 0 failing, 1 ignored.
5. **Run `cargo clippy --all-targets -- -D warnings`** — clean.
6. **Start with §5.1 — the two manual-testing bugs.** They
   were deferred mid-run with the user's agreement; they are
   the committed next step, ahead of ADR-0028.

### Note on the typing-surface matrix

`tests/typing_surface/` is **161 cells**, unchanged. One
cell — `where_expression::complex_and_or_expression_parses`
— used a column (`t`) that does not exist in its schema; the
new schema-existence diagnostic correctly flagged it, which
revealed the cell was not testing what it claimed. Its input
was corrected to a real column and the snapshot regenerated.
The matrix-snapshot discipline from handoff-17/18 still
applies: a failing cell with *correct* new behaviour →
update its snapshot; with *wrong* behaviour → the cell
earned its keep.