fix(welcome): notify the core after writing scratch; unstale the ledger

Review round 1 on #205, two findings, both accepted.

The greeting was written straight into the registry without calling
`notify_buffer_edit`. The window's `TextView` had been indexed while
`*scratch*` was empty, and newlines are zero-width to a painter working
from a stale line index — so the first TUI frame collapsed the whole
three-line greeting onto row 0. Every buffer-text assertion passed
because the buffer content was correct; only the rendering was wrong.
The edit is now captured, the registry borrow released, and the core
notified.

The pin that would have caught it paints a real frame and asserts the
second line occupies its own row AND that row 0 does not contain it —
both directions, because a one-direction check passes when everything
collapses upward. Bitten by dropping the notify call: row 1 comes back
empty with row 0 holding the lot, and it is the only pin that fails.

Second: the project docs still described the arc as it was two PRs ago.
`COHERENCE.md` §20 called 1b-2 in flight and the welcome buffer
unstarted; its arc list said 1b-3 remained; and the ledger's journey
lane header still read "1b-2 PR OPEN" while the 1b-3 block carried a
mangled "Framing only; no code" line left by an earlier edit. All now
describe the PR-head state per §25.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Lv428Fth9LRtffwJSsqH7T

COHERENCE.md

@@ -1575,19 +1575,20 @@ Establish the end-to-end workflow; treat regressions as release
 blockers. **State: runs to step 5; thin from step 6 (§2). Mostly wiring,
 and unusually cheap:** directory-argument handling (**done**: Journey
 Stage 1a); a find-file surface (**done**: #162 open-by-path, #165
-browsing); surfacing the LSP spawn failure with guidance (**in flight**:
-Journey Stage 1b-2, §1.2); a compile keybinding + `cargo build`/`test`
-default (**done**: Journey Stage 1b-1, #203, from the existing
+browsing); surfacing the LSP spawn failure with guidance (**done**: Journey Stage
+1b-2, #204, §1.2); a compile keybinding + `cargo build`/`test` default
+(**done**: Journey Stage 1b-1, #203, from the existing
 `ProjectKind::Rust` — **not** `Cargo`, see §24); a terminal keybinding
-(**done**: `C-c t`, #173); a welcome buffer. The journey acceptance
+(**done**: `C-c t`, #173); a welcome buffer (**in flight**: Journey
+Stage 1b-3). The journey acceptance
 suite (§19) is the ratchet that keeps it fixed — it **exists now**
 (`tests/journey_acceptance.rs`, Stage 1a), seeded with steps 2, 3 and 5,
 and carrying step 9 since #203.
 
-Journey Stage 1b is the named remainder, and it splits: **1b-1 — the
-compile binding + project-kind defaults — landed as #203**; **1b-2**
-(LSP spawn guidance, step 6) is in flight; **1b-3**, the welcome buffer
-(step 4), remains.
+Journey Stage 1b is the named remainder, and it splits: **1b-1** (the
+compile binding + project-kind defaults) landed as #203 and **1b-2**
+(LSP spawn guidance, step 6) as #204; **1b-3**, the welcome buffer
+(step 4), is in flight and completes the split.
 
 ### Priority 2: Make workspace and location explicit
 
@@ -1660,8 +1661,9 @@ implementation — this list is direction, not commitment):
    #165's dired buffer rather than growing a second directory surface.
    **Stage 1b-1 — landed (#203)**: the compile binding and project-kind
    defaults, with the prompt capturing its directory rather than
-   re-resolving it at accept time. **Stage 1b-2 — in flight**:
-   LSP-failure surfacing. **Stage 1b-3 — remaining**: welcome buffer.
+   re-resolving it at accept time. **Stage 1b-2 — landed (#204)**:
+   LSP-failure surfacing. **Stage 1b-3 — in flight**: the welcome
+   buffer and `M-x help`. With it the 1b split is complete.
 2. **Discovery surface** (P4): the describe/list/where-is command
    family, M-x rich rows, help unification, help prefix.
 3. **Transient keymap layer** (§6): the overlay scope + lifetime

docs/active-work.md

@@ -255,11 +255,11 @@ If it does not, stop and repair the remote/fetch configuration.
   never been enforced. Any CI job that compiles the `crdt` targets has to
   fix them first or it will be red on arrival.
 
-## Journey lane (P1) — 1a and 1b-1 MERGED; 1b-2 PR OPEN; 1b-3 REMAINS
+## Journey lane (P1) — 1a, 1b-1, 1b-2 MERGED; 1b-3 PR OPEN
 
-**Rewritten, not removed, at #203's merge.** Rule 4 removes a lane when
-its ARC is done; the journey arc is not — 1b-2 is in flight and 1b-3 is
-unframed. Stage 1a (#182/#183) and Stage 1b-1 (#203) are on `main` and
+**Rewritten, not removed.** Rule 4 removes a lane when its ARC is done;
+the journey arc is not — 1b-3 is the last stage of the 1b split and is
+still open. Stage 1a (#182/#183) and Stage 1b-1 (#203) are on `main` and
 their durable facts are in `docs/agent-handoff.md` §1, which is rule 4's
 precondition satisfied rather than deferred.
 
@@ -326,7 +326,8 @@ re-conflict on every merge.
 ## Journey Stage 1b-3 (P1) — IMPLEMENTED, PR OPEN
 
 - **Branch `journey-stage1b3-welcome`**, worktree `../pmacs-journey-1b3`,
-  based on `githubsucks/main` @ `1f290d5`. **Framing only; no code, no
+  based on `githubsucks/main` @ `1f290d5`, **integrated with `main` @
+  `5376af1`** (#204). **Implemented; PR #205 open.**
   `docs/journey-stage1b3-welcome-framing.md` revision 4, three
   review rounds closed (round 1: four findings; round 2: two acceptance
   holes plus a doc correction; round 3: a visibility mismatch and an

src/editor.rs

@@ -940,20 +940,29 @@ impl EditorState {
             // gets no greeting, not a failed launch.
             Err(_) => return,
         };
+        // Capture the edit and RELEASE the registry borrow before
+        // notifying: `notify_buffer_edit` borrows the registry itself.
         let registry = self.core.borrow().registry.clone();
-        let mut reg = registry.borrow_mut();
-        let Ok(buf) = reg.get_mut(buffer_id) else {
-            return;
-        };
-        if buf
-            .apply_edit(crate::buffer::EditOp::Insert {
+        let edit = {
+            let mut reg = registry.borrow_mut();
+            let Ok(buf) = reg.get_mut(buffer_id) else {
+                return;
+            };
+            let Ok(edit) = buf.apply_edit(crate::buffer::EditOp::Insert {
                 pos: 0,
                 bytes: text.as_bytes(),
-            })
-            .is_ok()
-        {
+            }) else {
+                return;
+            };
             buf.mark_clean();
-        }
+            edit
+        };
+        // Without this the greeting renders as ONE row on the first
+        // frame: the window's `TextView` indexed `*scratch*` while it
+        // was empty, and newlines are zero-width to a painter working
+        // from a stale line index. Every other direct-registry writer
+        // notifies for the same reason.
+        self.core.borrow_mut().notify_buffer_edit(buffer_id, &edit);
     }
 
     /// Restore the session saved under this desktop's key, if armed

tests/journey_acceptance.rs

@@ -2124,3 +2124,71 @@ fn journey_step6_a_missing_language_server_is_reported_not_swallowed() {
          is what made highlighting able to mask this"
     );
 }
+
+/// **N** — the greeting renders as separate rows on the **first frame**.
+///
+/// Writing to the registry without `notify_buffer_edit` leaves the
+/// window's `TextView` indexed against the empty `*scratch*` it was
+/// built for. Newlines are zero-width to a painter working from a stale
+/// line index, so the whole three-line greeting collapses onto row 0 —
+/// visible to a user, invisible to every buffer-text assertion above.
+///
+/// Falsified by dropping the `notify_buffer_edit` call in
+/// `finalize_local_launch`.
+#[test]
+fn journey_step4_the_welcome_paints_as_multiple_rows_on_the_first_frame() {
+    use pmacs::cell::{Cell, CellGrid, CellSize, Glyph};
+
+    let s = start_local();
+    let (rows, cols) = (12u32, 100u32);
+    let mut cells = vec![Cell::default(); (rows * cols) as usize];
+    let mut grid = CellGrid {
+        cells: &mut cells,
+        stride: cols,
+        size: CellSize::new(rows, cols),
+    };
+    let _ = pmacs::editor::paint_frame(
+        &s,
+        FrontendId::LOCAL,
+        &std::collections::HashMap::new(),
+        &mut grid,
+        CellSize::new(rows, cols),
+    );
+
+    let row_text = |row: u32| -> String {
+        (0..cols)
+            .map(
+                |column| match &cells[(row * cols + column) as usize].glyph {
+                    Glyph::Char(ch) => *ch,
+                    Glyph::Cluster(bytes) => std::str::from_utf8(bytes)
+                        .ok()
+                        .and_then(|t| t.chars().next())
+                        .unwrap_or(' '),
+                    Glyph::Continuation => ' ',
+                },
+            )
+            .collect::<String>()
+            .trim_end()
+            .to_owned()
+    };
+
+    assert!(
+        row_text(0).contains("Welcome to pmacs"),
+        "row 0 is the greeting's first line; got {:?}",
+        row_text(0)
+    );
+    // The discriminating half: with a stale TextView these land on row 0
+    // too, and row 1 is blank.
+    assert!(
+        row_text(1).contains("C-x C-f"),
+        "the second line must occupy its own row, not collapse into the \
+         first; row 1 = {:?}, row 0 = {:?}",
+        row_text(1),
+        row_text(0)
+    );
+    assert!(
+        !row_text(0).contains("C-x C-f"),
+        "and must not have been folded into row 0; got {:?}",
+        row_text(0)
+    );
+}