docs: ADR-0047 — demonstration overlay layer for casts/teaching (#22)

Accepted decision record for the in-app demo overlay: a --demo mode
that shows automatic keystroke badges ([TAB], [ENTER], …) and a
stealth Ctrl+]-delimited step-caption buffer, both as floating
black-on-yellow boxes at the output panel's bottom-right. All forks
user-confirmed; a /runda pass contributed 10 tightening findings.
Indexed in docs/adr/README.md.

docs/adr/README.md

@@ -52,3 +52,4 @@ This directory contains the project's ADRs, recorded per
 - [ADR-0044 — Relationship visualization (two-table connector diagrams)](0044-relationship-visualization.md) — **Accepted 2026-06-09; implemented 2026-06-10** (closes `requirements.md` V1; second `/runda` pass over the implementation; §3 last-resort helper line considered and rejected). Resolves **ADR-0016 OOS-1** and closes the open half of `requirements.md` **V1** ("a selected relationship as two tables joined by a line"). Renders a relationship as **Style A** (two structure boxes + connector). **Reach = "relationship-relevant"** (user-chosen over global / show-only): diagrams on the surfaces where the relationship is the *subject* — `show relationship <name>` (one full diagram), `show table <T>` (T's structure box then a **Relationships** section of **stacked compact** per-relationship diagrams — chosen over a focal-centred subgraph: no crossing lines, scales via scroll, two-boxes-wide fits any terminal), and relationship DDL echoes (`add`/`drop`/`modify relationship`); incidental DDL echoes (`add column`, `drop index`, `change column`, plain `create table`) keep the terse prose, via a `Diagram`|`Prose` render mode on `render_structure`. Reading convention **child(FK)-left / parent-right, arrow →, `n`…`1` cardinality**, applied uniformly; every box gets a **bold title row + rule** so the name can't read as a column. **Compound FKs** (ADR-0043) route one connector per positional pair + an explicit pairing line. **Width-aware** (first in the codebase) but **App-side**: `render_structure`/diagram rendering runs in `app.rs` (the worker only returns `TableDescription`s), a new `App::last_output_width` (set from `ui.rs`) drives side-by-side vs a **vertical-stack** fallback + last-resort "run `show relationship`" pointer; rendered once at command time, **no live reflow** (V4). `show relationship`'s worker path (`do_show_one`, prose-only) is restructured to return both endpoint `TableDescription`s. Styling reuses **ADR-0028** App-side styled runs (new classes: table-name/key/connector/cardinality/action) — no worker→UI contract change. **Partially supersedes ADR-0016 §5** (prose block replaced on relationship-subject surfaces, retained on incidental ones); extends §4 (layout width-awareness, still no cell truncation) and §6 (per-span theming). Tests: insta snapshots (single, compound, vertical fallback, helper line, self-referential, multi-rel `show table`) + width-threshold/routing unit tests + Tier-3 wiring; enumerated prose-fallout updates (`output_render.rs:121/135/793`, the relationships snapshot, `walking_skeleton.rs:477/530`). A `/runda` DA pass corrected three inverted-architecture claims (App-side rendering, untracked width, prose-in-worker show-relationship) before acceptance. OOS: user-configurable display setting (OOS-7), live reflow (V4), whole-DB ER export (V3), m:n (C4), ASCII fallback (ADR-0016 OOS-5)
 - [ADR-0045 — `create m:n relationship` convenience command (C4)](0045-mn-convenience.md) — **Accepted + implemented 2026-06-10** (closes `requirements.md` **C4**; all forks user-confirmed + a `/runda` DA pass that verified the `do_create_table` reuse against code and corrected the "no PK-less tables" assumption — advanced SQL `create table t (a int)` has none, so a parent-PK guard is retained). Implementation corrected a second ADR premise: "the walker already dispatches multiple nodes per entry word" held only in *advanced* mode — two simple-mode spots (dispatcher `decide`, completion continuation-merge) assumed ≤1 DSL form per entry word and were generalized **behaviour-preservingly** (dispatch reduces to the old single-candidate commit; completion merge gated on `simple_count > 1`). Junction echo wired (`render_create_m2n`, round-trips as SQL). `create m:n relationship from <T1> to <T2> [as <name>]` generates a junction table with one FK column per parent PK column, a **compound PK over all the FK columns** (the textbook junction — the pair is unique, no duplicate links), and **two 1:n relationships**, all in **one transaction = one undo step** (built by reusing `do_create_table`, which already takes `foreign_keys` + writes relationship metadata — no batch bracketing). Forks all user-chosen: junction PK = compound-over-FKs (vs surrogate serial / no PK); referential actions = **`CASCADE`** on delete+update (vs NO ACTION / RESTRICT); naming = auto `{T1}_{T2}` + optional `as` (vs auto-only); available in **both modes** (Simple-category DSL, like the sibling relationship commands). FK columns named `{parent_table}_{pk_column}` (disambiguates shared `id`; generalises to compound parents via ADR-0043), typed via `fk_target_type` (ADR-0011). A distinct `Command::CreateM2nRelationship` (not lowered to `CreateTable`) preserves command identity (X5) and lets the teaching echo speak in m:n terms. Cross-cutting wiring enumerated: separate `CREATE_M2N` `CommandNode` (own `help_id`/`usage_ids`), `("m","m:n")` completion composite, `HintMode`s, grammar-driven highlighting, `help`/`help create`, `parse_error_pedagogy` near-miss matrix, teaching echo. OOS: **self-referential m:n** (`from T to T`) refused outright (user-confirmed "full stop" — directional column-naming is more than this beginner convenience warrants); per-relationship action overrides; extra junction payload columns; m:n diagram echo; renaming the auto-generated relationships
 - [ADR-0046 — Schema sidebar focus/navigation mode and responsive input & hint layout (UI #20/#21/#23)](0046-sidebar-navigation-and-responsive-input-hint.md) — **Accepted + implemented 2026-06-10, phased A→B→C** (8 commits `9f5f76b`…`22bec61`; closes Gitea **#20** hint jumpiness, **#21** left-column improvements, **#23** long input — all forks user-confirmed, including the persistent show/hide toggle which is **deferred**: the Ctrl-O peek covers #21's "keystroke to show and hide"). Two decisions landed differently from the draft (recorded inline): relationship data on **`App`** not `SchemaCache` (DB2); the nav overlay clears **only the sidebar strip + a one-column gutter**, panels staying visible behind (DC2). Treats the three UI issues as one coupled decision because they share the terminal's width/height budget. **Phase A (input & hint):** the hint panel's height becomes a function of **terminal geometry, fixed between resizes** (not of hint content), eliminating the #20 jump at its source — measured catalog shows ≥ ~54-col right-column width never needs > 2 hint lines, so 3 lines is a rare narrow-terminal-only case; height buckets `H<40` compact (input 1 row + horizontal scroll / hint 2) vs `H≥40` comfortable (input 2 rows soft-wrap / hint 2), output `Min(5)` honoured first under degradation; input gains horizontal scroll (`input_scroll_offset`, single logical `String` — **not** I1 multi-line) and 2-row soft-wrap display when tall, preserving ADR-0027's 6-col indicator reserve. **Phase B (sidebar):** the 26-col Tables column is **kept but made optional and richer** (not deleted — pedagogy wins ties) — **width-derived session-only** visibility (visible iff width > 90 or a Ctrl-O peek is active — no stored field; hides at width ≤ 90 so the 90-col screencasts drop it; ADR-0015 format untouched), plus a **relationships panel** rendered narrow with endpoints broken at the arrow, ellipsized — a **separate sibling panel** that **overrides S2**'s nested-list extension model (relationships are cross-table). the full records live on a new **`App.relationships`** field (revised from the ADR's original `SchemaCache.relationship_details` at implementation — `SchemaCache` is walker-facing and needs only the names, kept in `relationships: Vec<String>`; details are UI-only, so `App` mirrors `app.tables` and avoids ~23 fixture edits), delivered by `Database::read_all_relationships` + an `AppEvent::RelationshipsRefreshed`; the two left panels split vertically with the relationships panel floored at 5 rows ("(none)" when empty) and capped at 50 % of the column (DB4). **Phase C (navigation mode):** **`Ctrl-O`** enters a focus cycle (Input → Tables → Relationships → Input; `Esc` exits) orthogonal to the ADR-0003 input mode — **`Ctrl-B` was rejected on review as the default tmux prefix** (unreachable inside tmux); the focused panel **expands to ~40–50 cols as a `Clear` overlay** (right panels stay unchanging underneath) and scrolls via **Up/Down (line) + PageUp/PageDown (page)** (context-rebind, reusing the output-scroll viewport mechanism), with an accent focus border; all non-nav keys inert in nav mode (and nav keys inert while a modal is open). Forks all user-chosen: keep-optional-richer (vs remove/narrow); navigation-mode (vs modeless modifier scroll); `Ctrl-O` (Ctrl-B rejected = tmux prefix); overlay (vs layout re-split); inert-non-nav-keys; geometry-fixed hint height; `H<40/≥40` thresholds; session-only persistence; Up/Down line-scroll; **separate relationships panel overriding S2**; **no hint-area toggle** (S4's stale "keyboard-toggleable" claim struck — never implemented, unwanted). A pre-build `/runda` DA pass drove these corrections: caught the `Ctrl-B`/tmux collision, the `SchemaCache` retype that would have broken completion, the 2-row-input/indicator placement, the missing nav-mode key disposition + modal gate, and three unreferenced requirements (S1 evolved, S2 overridden, S4 corrected); also cross-checked open issue **#22** (overlay/annotation layer — separate ADR, adjacent). OOS: true multi-line input (I1); readline shortcuts (I1b); cross-session sidebar persistence; output as a third nav focus; relationship search/edit from the panel; hint-area toggle; #22's annotation layer. Accepted consequence: the 90-col visibility threshold makes a terminal's output *narrower* when widened across the boundary (sidebar appears)
+- [ADR-0047 — Demonstration overlay layer (keystroke badges + step captions)](0047-demonstration-overlay-layer.md) — **Accepted 2026-06-10** (Gitea **#22**; no `requirements.md` item — tracked by issue + ADR per convention; all forks user-confirmed + a `/runda` pass that produced 10 tightening findings). An in-app **demonstration mode** (`--demo` flag / `RDBMS_PLAYGROUND_DEMO` env, **off by default, zero footprint when off**) that renders two transient overlays so `autocast` screencasts — and live teaching, and a future guided-lesson system — can show otherwise-invisible interactions. **Keystroke badges** (`[TAB]`, `[ENTER]`, `[UP]`, …): **automatic, app-detected** over a fixed set of glyph-less keys (the app already sees every key, so it re-records for free), label via a pure `demo_badge_label(&KeyEvent)`; the badge **auto-expires on a ~1.5 s timer** that extends the runtime's existing time-boxed-`recv` arm condition (`debounce.is_armed() || badge_pending`; expiry `Instant` in the runtime, `App.demo_badge` the render mirror — mirroring the `input` vs `input_indicator` split). **Step captions**: a **stealth, control-code-delimited input buffer** toggled by **`Ctrl+]`** (byte `0x1D` → arrives as `Char('5')+CONTROL`, verified against crossterm 0.29 `parse.rs:110-113`; chosen over `Ctrl+!`, which is **not a single ASCII byte so autocast cannot send it** — the same wall as arrow keys, R4) — typed characters accumulate **invisibly** (prompt untouched, no echo/history), `Backspace` edits, other keys inert, a second `Ctrl+]` **commits** to the caption box (empty commit dismisses); lives in pure-sync `App::update()`, **intercepted before the modal gate** so captions/badges work **over the load picker** (the `#24` projects cast). Both render as **floating black-on-yellow boxes at the output panel's inner bottom-right**, drawn **last over modals**, badge **stacked above** the caption, **no layout reflow**; caption **word-wraps to ≤ 3 lines** (3–5 rows), badge fixed 3 rows; clamp/skip guard for tiny terminals; a new **`App.last_output_area: Rect`** (set in `render_output_panel`) gives the top-level draw the anchor. Caption persists **until the next keystroke**; badge suppressed while capturing. Forks all user-chosen: `--demo` activation (vs hidden command / chord); automatic badges (vs scripted); stealth buffer (vs typed-command / preloaded-file); floating bottom-right boxes (vs HUD / banner / subtitle); `Ctrl+]` trigger; wrap-to-3-line captions; ~1.5 s badge / next-keystroke caption timing. Tested test-first across Tier 1 (label fn, capture state machine incl. over-modal + demo-off gate, nearest-deadline helper), Tier 2 (insta snapshots: badge/caption/both-stacked at 90×26 light+dark, short-terminal clamp), Tier 3 (`--demo` plumbing, badge set/suppressed, caption-without-input wiring), CLI (`--demo` parse + env fallback) — with an **honest limit** noted: the `tokio` timer wiring inside `run_loop` is exercised via the pure pieces + Tier-3 plumbing, not a standalone integration test of the timeout. OOS: scripted/manual badge push; badges for glyph keys; configurable styling/placement; the guided-lesson system itself (own ADR); cross-session/-switch persistence; localised caption content; arrow-only cast interactions (output-pane scroll). Implementation phased **A** (`--demo` plumbing) → **B** (badges) → **C** (captions)