feat(git): commit graph in history view and cross-spawn everywhere

- render a VSCode-style commit graph in the source control history:
  lane-assignment algorithm, SVG strip with colored rails, merge and
  branch curves, commit dots, and branch/tag badges per commit
- /commits returns parents and ref decorations across all branches
  (--branches --remotes --tags --topo-order) using unit-separator
  fields so pipes in commit subjects can't break parsing
- collect stats via a single --shortstat pass instead of one
  `git show --stat` call per commit; raise the history limit to 50
- replace child_process spawn with cross-spawn in all runtimes,
  routes, and services: it resolves .cmd shims and PATHEXT on
  Windows (fixing taskmaster's npx invocations) and delegates to
  native spawn elsewhere, removing the per-file win32 ternaries
- unit tests for the log parser and lane assignment

src/components/git-panel/view/history/CommitGraphStrip.tsx

@@ -0,0 +1,95 @@
+import type { CommitGraphRow } from '../../utils/commitGraph';
+import { laneColor } from '../../utils/commitGraph';
+
+// Geometry: each lane is a fixed-width column; the commit dot sits at NODE_Y
+// inside a fixed-height top zone (matching the collapsed row header), and
+// plain rails continue below it so lines stretch through expanded content.
+const LANE_WIDTH = 12;
+const NODE_ZONE_HEIGHT = 56;
+const NODE_Y = 28;
+const NODE_RADIUS = 3.5;
+const STROKE_WIDTH = 2;
+
+const laneX = (lane: number) => lane * LANE_WIDTH + LANE_WIDTH / 2;
+
+type CommitGraphStripProps = {
+  row: CommitGraphRow;
+};
+
+export default function CommitGraphStrip({ row }: CommitGraphStripProps) {
+  const width = row.laneCount * LANE_WIDTH;
+  const nodeX = laneX(row.nodeLane);
+  const nodeColor = laneColor(row.nodeLane);
+
+  return (
+    <div aria-hidden className="relative shrink-0 self-stretch overflow-hidden" style={{ width }}>
+      <svg
+        className="absolute left-0 top-0"
+        width={width}
+        height={NODE_ZONE_HEIGHT}
+        fill="none"
+      >
+        {/* Lines passing straight through the row */}
+        {row.passThrough.map((lane) => (
+          <path
+            key={`pass-${lane}`}
+            d={`M ${laneX(lane)} 0 V ${NODE_ZONE_HEIGHT}`}
+            stroke={laneColor(lane)}
+            strokeWidth={STROKE_WIDTH}
+          />
+        ))}
+
+        {/* The node's own lane arriving from above / continuing below */}
+        {row.hasTopContinuation && (
+          <path d={`M ${nodeX} 0 V ${NODE_Y}`} stroke={nodeColor} strokeWidth={STROKE_WIDTH} />
+        )}
+        {row.hasParentContinuation && (
+          <path d={`M ${nodeX} ${NODE_Y} V ${NODE_ZONE_HEIGHT}`} stroke={nodeColor} strokeWidth={STROKE_WIDTH} />
+        )}
+
+        {/* Extra children merging into the node from the row above */}
+        {row.inbound.map((lane) => (
+          <path
+            key={`in-${lane}`}
+            d={`M ${laneX(lane)} 0 Q ${laneX(lane)} ${NODE_Y} ${nodeX} ${NODE_Y}`}
+            stroke={laneColor(lane)}
+            strokeWidth={STROKE_WIDTH}
+          />
+        ))}
+
+        {/* Extra parents branching out of the node toward the row below */}
+        {row.outbound.map((lane) => (
+          <path
+            key={`out-${lane}`}
+            d={`M ${nodeX} ${NODE_Y} Q ${laneX(lane)} ${NODE_Y} ${laneX(lane)} ${NODE_ZONE_HEIGHT}`}
+            stroke={laneColor(lane)}
+            strokeWidth={STROKE_WIDTH}
+          />
+        ))}
+
+        {/* Commit dot — slightly larger for merge/fork points */}
+        <circle
+          cx={nodeX}
+          cy={NODE_Y}
+          r={row.inbound.length > 0 || row.outbound.length > 0 ? NODE_RADIUS + 0.5 : NODE_RADIUS}
+          fill={nodeColor}
+        />
+      </svg>
+
+      {/* Rails continuing below the node zone (through expanded content) */}
+      {row.bottomLanes.map((lane) => (
+        <div
+          key={`rail-${lane}`}
+          className="absolute"
+          style={{
+            left: laneX(lane) - STROKE_WIDTH / 2,
+            top: NODE_ZONE_HEIGHT,
+            bottom: 0,
+            width: STROKE_WIDTH,
+            backgroundColor: laneColor(lane),
+          }}
+        />
+      ))}
+    </div>
+  );
+}

src/components/git-panel/view/history/CommitHistoryItem.tsx

@@ -1,8 +1,11 @@
-import { ChevronDown, ChevronRight } from 'lucide-react';
+import { ChevronDown, ChevronRight, GitBranch, Tag } from 'lucide-react';
 import { useMemo } from 'react';
 import type { GitCommitSummary } from '../../types/types';
+import type { CommitGraphRow } from '../../utils/commitGraph';
+import { laneColor } from '../../utils/commitGraph';
 import { getStatusBadgeClass, parseCommitFiles } from '../../utils/gitPanelUtils';
 import GitDiffViewer from '../shared/GitDiffViewer';
+import CommitGraphStrip from './CommitGraphStrip';
 
 function formatDate(dateString: string): string {
   return new Date(dateString).toLocaleDateString('en-US', {
@@ -12,12 +15,36 @@ function formatDate(dateString: string): string {
   });
 }
 
+// One "HEAD -> main" / "origin/x" / "tag: v1" decoration pill next to the
+// commit message, tinted with the commit's graph lane color.
+function RefBadge({ refName, color }: { refName: string; color: string }) {
+  const isTag = refName.startsWith('tag: ');
+  const isHead = refName.startsWith('HEAD -> ');
+  const label = isTag ? refName.slice(5) : isHead ? refName.slice(8) : refName;
+
+  return (
+    <span
+      className="inline-flex max-w-40 items-center gap-1 rounded-full border px-1.5 py-px text-[10px] font-medium leading-4"
+      style={{
+        borderColor: color,
+        color,
+        backgroundColor: isHead ? `${color}22` : 'transparent',
+      }}
+      title={refName}
+    >
+      {isTag ? <Tag className="h-2.5 w-2.5 shrink-0" /> : <GitBranch className="h-2.5 w-2.5 shrink-0" />}
+      <span className="truncate">{label}</span>
+    </span>
+  );
+}
+
 type CommitHistoryItemProps = {
   commit: GitCommitSummary;
   isExpanded: boolean;
   diff?: string;
   isMobile: boolean;
   wrapText: boolean;
+  graphRow?: CommitGraphRow;
   onToggle: () => void;
 };
 
@@ -27,6 +54,7 @@ export default function CommitHistoryItem({
   diff,
   isMobile,
   wrapText,
+  graphRow,
   onToggle,
 }: CommitHistoryItemProps) {
   const fileSummary = useMemo(() => {
@@ -34,8 +62,12 @@ export default function CommitHistoryItem({
     return parseCommitFiles(diff);
   }, [diff]);
 
+  const badgeColor = graphRow ? laneColor(graphRow.nodeLane) : 'var(--color-primary, #0ea5e9)';
+
   return (
-    <div className="border-b border-border last:border-0">
+    <div className="flex border-b border-border last:border-0">
+      {graphRow && <CommitGraphStrip row={graphRow} />}
+      <div className="min-w-0 flex-1">
       <button
         type="button"
         aria-expanded={isExpanded}
@@ -48,6 +80,13 @@ export default function CommitHistoryItem({
         <div className="min-w-0 flex-1">
           <div className="flex items-start justify-between gap-2">
             <div className="min-w-0 flex-1">
+              {commit.refs && commit.refs.length > 0 && (
+                <span className="mb-0.5 flex flex-wrap gap-1">
+                  {commit.refs.map((refName) => (
+                    <RefBadge key={refName} refName={refName} color={badgeColor} />
+                  ))}
+                </span>
+              )}
               <p className="truncate text-sm font-medium text-foreground">{commit.message}</p>
               <p className="mt-1 text-sm text-muted-foreground">
                 {commit.author}
@@ -145,6 +184,7 @@ export default function CommitHistoryItem({
           </div>
         </div>
       )}
+      </div>
     </div>
   );
 }

src/components/git-panel/view/history/HistoryView.tsx

@@ -1,6 +1,7 @@
 import { History, RefreshCw } from 'lucide-react';
-import { useCallback, useState } from 'react';
+import { useCallback, useMemo, useState } from 'react';
 import type { GitDiffMap, GitCommitSummary } from '../../types/types';
+import { computeCommitGraph } from '../../utils/commitGraph';
 import CommitHistoryItem from './CommitHistoryItem';
 
 type HistoryViewProps = {
@@ -22,6 +23,15 @@ export default function HistoryView({
 }: HistoryViewProps) {
   const [expandedCommits, setExpandedCommits] = useState<Set<string>>(new Set());
 
+  // Lane layout for the commit graph; rows align 1:1 with recentCommits.
+  // Older API responses without `parents` degrade to plain rows (no strip).
+  const graphRows = useMemo(() => {
+    if (!recentCommits.some((commit) => commit.parents !== undefined)) {
+      return null;
+    }
+    return computeCommitGraph(recentCommits);
+  }, [recentCommits]);
+
   const toggleCommitExpanded = useCallback(
     (commitHash: string) => {
       const isExpanding = !expandedCommits.has(commitHash);
@@ -59,7 +69,7 @@ export default function HistoryView({
         </div>
       ) : (
         <div className={isMobile ? 'pb-4' : ''}>
-          {recentCommits.map((commit) => (
+          {recentCommits.map((commit, index) => (
             <CommitHistoryItem
               key={commit.hash}
               commit={commit}
@@ -67,6 +77,7 @@ export default function HistoryView({
               diff={commitDiffs[commit.hash]}
               isMobile={isMobile}
               wrapText={wrapText}
+              graphRow={graphRows?.[index]}
               onToggle={() => toggleCommitExpanded(commit.hash)}
             />
           ))}