fix(dashboard): stop Chat Latest button jumping under the cursor

Center the jump-to-latest chip with margin-inline auto instead of
transform:translateX(-50%) so global .btn transform transitions and
:active scale cannot shift it sideways in Quick Chat and full Chat.

.changeset/chat-jump-to-latest-active-transform.md

@@ -2,6 +2,6 @@
 "@runfusion/fusion": patch
 ---
 
-summary: Fix the Chat View "Latest" button shifting sideways out from under the cursor when clicked.
+summary: Stop the Chat/Quick Chat "Latest" button from jumping when the cursor moves near or presses it.
 category: fix
-dev: `.chat-jump-to-latest:active` now composes `translateX(-50%) scale(0.97)` so the global `.btn:active` transform no longer replaces the centering transform.
+dev: Center `.chat-jump-to-latest` with left/right + margin-inline auto instead of transform:translateX(-50%) so global `.btn` transform transitions and :active scale cannot shift the chip sideways.

packages/dashboard/app/components/ChatView.css

@@ -1035,20 +1035,21 @@ The thread-wide Markdown/plain render toggle (`.chat-thread-header-render-toggle
   word-break: break-word;
 }
 
-.chat-jump-to-latest {
-  position: absolute;
-  left: 50%;
-  bottom: calc(var(--space-xl) * 3);
-  transform: translateX(-50%);
-  z-index: 2;
-}
-
 /*
 FNXC:ChatView 2026-07-22-00:00:
 The Latest button is centered with transform: translateX(-50%), so the global .btn:active { transform: scale(0.97) } rule must not replace that transform wholesale — doing so shifted the button half its width sideways on mousedown, out from under the cursor mid-click. Compose both transforms on :active instead (same fix as .devserver-log-viewer__new-logs-button).
+
+FNXC:ChatView 2026-07-23-18:15:
+Compose-on-:active was still fragile: same specificity as `.btn:active` can lose the cascade war (SelectionCommentPopover regressed the same way), and the shared `.btn { transition: transform }` made any transform churn feel like the chip jumps when the cursor moves near/over it in Quick Chat and full Chat. Center with left/right + margin-inline auto + width: fit-content so positioning no longer owns `transform`. Global `.btn:active` scale then applies in place around the geometric center without a sideways teleport. Covers session + room jump buttons (shared class), floating Quick Chat, main Chat view, and mobile.
 */
-.chat-jump-to-latest:active {
-  transform: translateX(-50%) scale(0.97);
+.chat-jump-to-latest {
+  position: absolute;
+  left: 0;
+  right: 0;
+  width: fit-content;
+  margin-inline: auto;
+  bottom: calc(var(--space-xl) * 3);
+  z-index: 2;
 }
 
 .chat-message--user {

packages/dashboard/app/components/__tests__/ChatView.jump-to-latest.test.ts

@@ -0,0 +1,54 @@
+import { readFileSync } from "node:fs";
+import { resolve } from "node:path";
+import { describe, expect, it } from "vitest";
+
+/*
+FNXC:ChatView 2026-07-23-18:15:
+Regression guard for the Latest jump chip teleporting under the cursor. The control is shared by
+main Chat, floating Quick Chat, and room threads (`.chat-jump-to-latest`). Centering must not use
+`transform: translateX(-50%)` because global `.btn:active { transform: scale(0.97) }` and
+`.btn { transition: transform }` replace or animate that translate and shift the chip sideways when
+the pointer approaches or presses it. jsdom cannot hit-test the mid-press jump, so the invariant is
+asserted on the stylesheet: every transform rule that targets the jump class is forbidden, and the
+base rule must center with left/right + margin-inline auto + width: fit-content.
+*/
+const chatViewCss = readFileSync(resolve(__dirname, "../ChatView.css"), "utf8");
+
+function uncomment(css: string): string {
+  return css.replace(/\/\*[\s\S]*?\*\//g, "");
+}
+
+function collectJumpBlocks(css: string): Array<{ selector: string; block: string }> {
+  const blocks: Array<{ selector: string; block: string }> = [];
+  const rulePattern = /([^{}]+)\{([^{}]*)\}/g;
+  for (const match of uncomment(css).matchAll(rulePattern)) {
+    const selector = match[1].trim();
+    if (selector.split(",").some((part) => part.trim().includes(".chat-jump-to-latest"))) {
+      blocks.push({ selector, block: match[2] });
+    }
+  }
+  return blocks;
+}
+
+describe("ChatView jump-to-latest centering", () => {
+  it("centers without transform so btn press/hover transitions cannot shift the chip sideways", () => {
+    const blocks = collectJumpBlocks(chatViewCss);
+    expect(blocks.length).toBeGreaterThanOrEqual(1);
+
+    const base = blocks.find(({ selector }) => selector.trim() === ".chat-jump-to-latest");
+    expect(base, "base .chat-jump-to-latest rule must exist").toBeDefined();
+    expect(base!.block).toMatch(/left\s*:\s*0/);
+    expect(base!.block).toMatch(/right\s*:\s*0/);
+    expect(base!.block).toMatch(/margin-inline\s*:\s*auto/);
+    expect(base!.block).toMatch(/width\s*:\s*fit-content/);
+    expect(base!.block).not.toMatch(/transform\s*:/);
+    expect(base!.block).not.toMatch(/translateX\s*\(/);
+
+    for (const { selector, block } of blocks) {
+      expect(
+        block,
+        `jump rule "${selector}" must not own transform (global .btn:active/hover transitions own it)`,
+      ).not.toMatch(/transform\s*:/);
+    }
+  });
+});