81 lines
3.8 KiB
Markdown
81 lines
3.8 KiB
Markdown
# pmacs-gpu status band — framing pass
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Date: 2026-06-12. The GPU window has no status surface: no buffer
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name, no modified flag, no cursor position, no diagnostic counts
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(the M4.6 parity session deferred counts here for exactly this
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reason). Survey facts: `InstanceMessage::ModeLine(Vec<Cell>)` has
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sat reserved-but-unused since day one; `BufferSnapshot` carries no
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name/modified; glyphon's `prepare()` takes `&[TextArea]` so a second
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band area is structurally cheap; five geometry sites assume text
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runs to the surface bottom (`estimated_visible_lines`,
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`TextBounds.bottom`, the minimap height pair, the edge-scroll
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bottom band).
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## Q#S1 — where status facts come from
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**Stance: split by authority and freshness.**
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- **Locally derived, per frame**: cursor L:C (from `own_cursor` ×
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`current_line_starts` — the *optimistic* caret, so the readout
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tracks typing bursts instead of lagging a round trip behind
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them), and the scroll indicator (`scroll_top` × visible ×
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total, the TUI's All/Top/Bot/NN% formula).
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- **Instance-authoritative, on the wire**: buffer name, modified
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flag, exact whole-file diagnostic counts. A new additive variant
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(protocol v8, ladder continues on the v6 floor):
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`StatusFacts { buffer_id, name, modified, diag_errors,
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diag_warnings }`, emitted by the semantic producer when any fact
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changes (cached-compare, like `FileStyleSummary`; counts piggyback
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the diag-store epoch from the parity session).
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Rejected: populating the reserved `ModeLine(Vec<Cell>)`. It is
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grid-shaped — pre-formatted styled cells — which bakes the TUI's
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layout into a frontend that does its own, and a daemon-formatted
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L:C would visibly lag the optimistic caret. The variant stays
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reserved for grid use. Also rejected: counting marked lines in
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`FileStyleSummary` as the counts — that counts *lines*, the TUI
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counts *diagnostics*; two frontends showing different numbers for
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the same buffer reads as a bug.
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## Q#S2 — band rendering
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**Stance: quad + second `TextArea`.** A `STATUS_BAND_HEIGHT` (26px)
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strip at the surface bottom: a background quad through the existing
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quad pipeline, and a one-line cosmic-text `Buffer` shaped only when
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the composed status string changes, passed as a second `TextArea`
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in the same `prepare()` call. Left: `name *` (modified star).
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Right: `E:n W:n L:C NN%` — diag counts colored by the severity
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palette, omitted when zero.
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## Q#S3 — geometry
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**Stance: one helper, no scattered arithmetic.** `text_area_bottom
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(surface_height) = height - STATUS_BAND_HEIGHT` feeds every site
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that assumed the surface bottom: `estimated_visible_lines`,
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`TextBounds.bottom`, the minimap height pair
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(`minimap_band_contains` / `minimap_y_to_line` / painters), and the
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edge-scroll bottom band. The minimap keeps its own `MINIMAP_BOTTOM`
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inset *above* the band.
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## Predicted findings (categorical bets)
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1. **A missed bottom-assuming site**: something still measures to
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the raw surface bottom — surfaces as content drawn under the
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band, or a hit-test/scroll off-by-a-line at the window bottom.
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2. **Visible-lines ripple**: shrinking `estimated_visible_lines`
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perturbs viewport/scroll math tuned to the old height — surfaces
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as a flickering scroll indicator or an unreachable last line.
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3. **Optimistic L:C flicker**: the locally derived readout jumps
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when a daemon `CursorByte` confirms through the floor-release
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path mid-burst — cosmetic, but noticeable enough to get reported.
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## Session plan
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Order: geometry + band rendering with the local facts (L:C, scroll)
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→ v8 `StatusFacts` wire + daemon emission + name/modified/counts →
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tests/polish. Manual validation: resize the window, type a burst
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mid-file (L:C tracks), scroll to both extremes (Top/Bot), introduce
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and fix an error (counts appear/vanish), edit (modified star), and
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re-run the minimap + edge auto-scroll gestures against the new
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bottom edge.
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