From 0902a9e173a3e579776d989e4bc7778a486d10c7 Mon Sep 17 00:00:00 2001
From: Levi Neuwirth <ln@levineuwirth.org>
Date: Thu, 21 May 2026 11:30:29 -0400
Subject: [PATCH] Revert "session 5 fixup: clear styling on CrdtOp ..."
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The clear-on-CrdtOp change broke the producer's incremental-update
contract. The producer ships dirty-range spans only on `full=false`
frames; the frontend is expected to retain non-dirty spans across
edits. Emptying both vectors meant the frontend ended up with only
the small dirty-range spans, missing the rest of the viewport — all
colors disappeared after an edit.

Reverting here. The proper fix lives in pmacs core (T M11.7):
producer must force `full=true` on generation transitions so the
frontend gets a complete replacement set on every text edit. Once
that lands, session-5's CrdtOp handler doesn't need to clear
anything — the next frame's `full=true` does it via
`replace_style_spans` / `replace_decorations`.

This reverts commit 49785c4. Returns the consumer behavior to
session-5's original "one-frame stale" artifact pending the core
fix.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
---
 pmacs-gpu/src/main.rs | 52 +++++++++++++++++++------------------------
 1 file changed, 23 insertions(+), 29 deletions(-)

diff --git a/pmacs-gpu/src/main.rs b/pmacs-gpu/src/main.rs
index 7e6fa73..e9f980e 100644
--- a/pmacs-gpu/src/main.rs
+++ b/pmacs-gpu/src/main.rs
@@ -410,13 +410,13 @@ impl State {
     /// (avoids the re-shape cost when an unchanged buffer ticks).
     ///
     /// Replaces the rope text and routes through `reshape` so the
-    /// rich-text rendering uses the current `current_spans` and
-    /// `current_decorations`. The `CrdtOp` arm of
-    /// [`Self::apply_attach_message`] clears both vectors before
-    /// calling `set_text`, so post-edit text never renders with
-    /// pre-edit-position colors. Brief uncolored window between an
-    /// edit and the daemon's next styling frame is the accepted
-    /// tradeoff (see that arm's doc comment for the rationale).
+    /// rich-text rendering uses the current `current_spans`. When
+    /// called from the `CrdtOp` path (text shifted under existing
+    /// spans) the spans are momentarily stale relative to the new
+    /// byte positions — `reshape` clamps via `range.end.min(text_len)`
+    /// so rendering is safe, but visual styling may be off until the
+    /// daemon's next `StyleSpans` frame catches up. A real artifact;
+    /// classified as a session-4 known limitation rather than a bug.
     fn set_text(&mut self, text: &str) {
         if self.current_text == text {
             return;
@@ -498,28 +498,22 @@ impl State {
                     eprintln!("pmacs-gpu: CrdtOp import failed: {e:?}");
                     return None;
                 }
-                // **Invalidate styling on text-shift.** The current
-                // spans + decorations index into byte positions of
-                // the *pre-edit* text. Once `set_text` swaps in the
-                // post-edit text, those positions no longer
-                // correspond to the right characters, so painting
-                // them produces wrong-character-colored fragments
-                // (the session-5 manual-validation finding: probe
-                // #3, "edit at a diagnostic boundary leaves stale
-                // color fragments"). The session-4 PR documented
-                // this as a "one-frame stale" artifact; in practice
-                // it stretches to the full LSP re-analysis cycle
-                // (100ms–5s), making the wrong-color period
-                // visible for human-perceptible durations.
-                //
-                // The fix is to drop both vectors here. Tree-sitter
-                // re-emits StyleSpans almost immediately (one
-                // frame after CrdtOp lands daemon-side); LSP
-                // decorations re-emit when clangd republishes.
-                // Cost: a brief uncolored window after each edit;
-                // gain: no wrong-position color persists.
-                self.current_spans.clear();
-                self.current_decorations.clear();
+                // NOTE: `current_spans` / `current_decorations` index
+                // into the *pre-edit* byte positions. The producer's
+                // next render frame (in pmacs core, post-T M11.7
+                // generation-transition fix) ships `full=true`
+                // styling for buffers whose generation advanced, so
+                // the next message replaces the stale items
+                // wholesale via `replace_style_spans` /
+                // `replace_decorations`. The single-frame gap
+                // between CrdtOp arrival and that next frame paints
+                // styling at stale byte positions — the session-4
+                // documented "one-frame stale" artifact. A previous
+                // attempt to fix it by clearing both vectors here
+                // (`49785c4`) was reverted because the producer's
+                // *incremental* updates ship dirty-range spans only,
+                // and an emptied cache loses the non-dirty viewport
+                // styling entirely.
                 let text = doc.get_text(LORO_TEXT_CONTAINER).to_string();
                 self.set_text(&text);
                 None