feat(web): PDF adjust v2 — re-selection replaces the extent; vertical grip clamp

Multi-line partial extents ("line 1's tail + the first words of line
2") were inexpressible with one-rect-per-drag grips, and the vertical
drags produced sliver rects whose text recompute swept fragments. The
web's re-selection uses what creation already uses: a selection made
during a rect-edge session is intercepted in checkPDFSelectionFor —
rects rebuild from the selection's per-line client rects, text re-reads
via the deduped glyph boxes, saved immediately (grip release-to-save
parity), and the create popover is suppressed for that gesture.

Vertical grip drags clamp to the rect's OWN line box (band ±quarter
height) — multi-line changes go through re-selection, slivers are gone.

Also verifies clean under the duplicated text-layer span sets (the
fork's pdf.js render never clears .textLayer — open bug): the text
recompute dedupes by glyph overlap.

CDP-verified end-to-end: session → multi-line selection → 6-rect
extent + clean text persisted (PUT 200); create popover correctly
suppressed during the session.

web/src/reader/reader.ts

@@ -1798,8 +1798,12 @@ document.addEventListener("alpine:init", () => {
       if (!map || !r) return;
       const vertical = edge === "left" || edge === "right";
       // Band: the rect's y-range widened to catch neighbouring line
-      // boundaries (horizontal-edge drags snap to line tops/bottoms).
-      const bandPad = vertical ? 0.002 : Math.max(r[3] * 0.75, 0.008);
+      // boundaries — but only ±quarter height now: a vertical drag adjusts
+      // THIS line box's height and can no longer swallow a neighbouring
+      // line (that produced sliver rects whose text recompute swept
+      // fragments — "some 14ng that scholars…"). Multi-line changes go
+      // through re-selection below.
+      const bandPad = vertical ? 0.002 : Math.max(r[3] * 0.25, 0.004);
       const bandTop = r[1] - bandPad;
       const bandBottom = r[1] + r[3] + bandPad;
       const band = this.pdfCharBoxes(map.doc, bandTop, bandBottom);
@@ -2150,6 +2154,47 @@ document.addEventListener("alpine:init", () => {
       const range = sel.getRangeAt(0);
       const text = sel.toString().replace(/\s+/g, " ").trim();
       if (!text) return;
+      // Adjust re-selection (v2): a selection made during a rect-edge
+      // session REPLACES the working extent — any lines, partial lines
+      // (the exact gap the grips could not express). Rects rebuild from
+      // the selection's line boxes, text re-reads, saved immediately:
+      // the grips' release-to-save parity.
+      if (this.pdfAdjust) {
+        const canvasRect =
+          (doc.querySelector("#canvas canvas") as HTMLElement) ||
+          (doc.querySelector("img") as HTMLElement);
+        const dr = canvasRect?.getBoundingClientRect();
+        if (!dr || !dr.width || !dr.height) return;
+        const rects: number[][] = [];
+        for (const r of range.getClientRects()) {
+          const x = (r.left - dr.left) / dr.width;
+          const y = (r.top - dr.top) / dr.height;
+          const w = r.width / dr.width;
+          const h = r.height / dr.height;
+          if (w > 0 && h > 0) rects.push([x, y, w, h]);
+        }
+        if (!rects.length) return;
+        const t = this.pdfTextForRects(doc, rects);
+        if (!t) {
+          showToast("Highlights can't be empty", "error");
+          return;
+        }
+        const session = this.pdfAdjust;
+        session.committed = true;
+        this.cancelPdfAdjust();
+        const p = this.selectionPopover;
+        p.id = session.id;
+        p.pdfPage = session.page;
+        p.pdfRects = rects;
+        p.text = t;
+        this.saveHighlightChanges();
+        try {
+          sel.removeAllRanges();
+        } catch {
+          /* doc may be gone */
+        }
+        return;
+      }
       // Denominator: the element whose post-transform screen rect IS
       // the visible page. For PDFs that's the rendered canvas — pdf.js
       // scales <html> by 1/devicePixelRatio, so documentElement's rect