diff --git a/coverage/xyzac-trt-tool-preview.report.json b/coverage/xyzac-trt-tool-preview.report.json
index b98851f..4553f24 100644
--- a/coverage/xyzac-trt-tool-preview.report.json
+++ b/coverage/xyzac-trt-tool-preview.report.json
@@ -102,11 +102,11 @@
     },
     {
       "path": "web/react/src/App.tsx",
-      "sha256": "e8d8beee65031cdcb70e8c5ab5b59db90e6b93ee2ac229fc4894d6da07caaeed"
+      "sha256": "154f6d2cbe9003a6d217e4d77089a739b275767c66e36839b6b6ae64ed11cbbd"
     },
     {
       "path": "web/react/src/styles.css",
-      "sha256": "0c523d532688228e29bcad6b828733a2f6b542cdb544584264c2f8d20ac9fad4"
+      "sha256": "1b0ee61a798338b6de901e60e17f71a7569eb04abda49f7eaa4a679cb22e6d2a"
     },
     {
       "path": "wasm-core/src/sim_task.c",
@@ -383,7 +383,7 @@
     }
   },
   "release_status": "STOP_RELEASE",
-  "report_sha256": "8fceb9e6f6af1089b405fd7b57aec455fc11b34ae5dc81b59448ae1469472a73",
+  "report_sha256": "54c3d3f24b7cd7ef58f7b6a480a8ba91b6d9309962368c85571711053eb85abc",
   "schema": "xyzac-trt-tool-preview-report.v1",
   "status": "verified",
   "task_id": "RTCP-10-TOOL-PREVIEW",
diff --git a/coverage/xyzac-trt-wasm-authority-audit.report.json b/coverage/xyzac-trt-wasm-authority-audit.report.json
index 22f9268..a8fdf10 100644
--- a/coverage/xyzac-trt-wasm-authority-audit.report.json
+++ b/coverage/xyzac-trt-wasm-authority-audit.report.json
@@ -205,7 +205,7 @@
     "recovery": "Chromium SIGKILL/profile-reopen, corruption detection and Firefox OPFS round-trip are verified"
   },
   "release_status": "STOP_RELEASE",
-  "report_sha256": "960537fe609868696cecacac63eb693adf11cc37406c7b098e653a914d0f5365",
+  "report_sha256": "24d166bbe8bf6ceac45c6f7c67cc2b9fccbc61c28f5412540193d955efe2d851",
   "scans": {
     "js_gcode_matches": [
       {
@@ -1496,7 +1496,7 @@
       "files": [
         {
           "path": "web/react/src/App.tsx",
-          "sha256": "e8d8beee65031cdcb70e8c5ab5b59db90e6b93ee2ac229fc4894d6da07caaeed"
+          "sha256": "154f6d2cbe9003a6d217e4d77089a739b275767c66e36839b6b6ae64ed11cbbd"
         },
         {
           "path": "web/react/src/ThreeMachineView.tsx",
@@ -1548,7 +1548,7 @@
         },
         {
           "path": "web/react/src/store.ts",
-          "sha256": "98a2634b0658d55bd1874c13196b7ac4ffffcdc9ff4246882b81147dad65523d"
+          "sha256": "2f415556da16d1ea4541d24e4a41fecfef316c7d45e5838f2cdf5d04ffa4d94e"
         },
         {
           "path": "web/react/src/test_xyzac_threejs.mjs",
diff --git a/coverage/xyzac-trt-wasm-only-release-gate.report.json b/coverage/xyzac-trt-wasm-only-release-gate.report.json
index 3afe725..711477e 100644
--- a/coverage/xyzac-trt-wasm-only-release-gate.report.json
+++ b/coverage/xyzac-trt-wasm-only-release-gate.report.json
@@ -96,7 +96,7 @@
   "failure_samples": [],
   "input": {
     "path": "coverage/xyzac-trt-web-wasm-parity.report.json",
-    "sha256": "f1664a422345d7974476a233de23bbebe784ef48d78422e66b3e44103295b47b"
+    "sha256": "090610e8912ff5e8e5537021674e4b6a8c043a148e1da1f9b44cebb42c2b468b"
   },
   "known_blockers": [
     "STOP_RELEASE is intentional until an owner authorizes scope expansion"
@@ -104,7 +104,7 @@
   "outputs": [],
   "release_decision": "selected_case_verified_but_release_stopped_by_scope_exclusions",
   "release_status": "STOP_RELEASE",
-  "report_sha256": "70ce954815cc9b7874bd7be3e0ed373fd9ad6ce9fb3b1af68ff9f70907c39b5a",
+  "report_sha256": "686b29b3118c1b9c60aceb2ea5d76fe83688fbad6b273ae270aa5114237d4e8e",
   "schema": "xyzac-trt-wasm-only-release-gate.v1",
   "status": "verified",
   "task_id": "RELEASE-00"
diff --git a/coverage/xyzac-trt-web-wasm-parity.report.json b/coverage/xyzac-trt-web-wasm-parity.report.json
index de9a476..6960bf4 100644
--- a/coverage/xyzac-trt-web-wasm-parity.report.json
+++ b/coverage/xyzac-trt-web-wasm-parity.report.json
@@ -101,12 +101,12 @@
     "coverage/xyzac-trt-source-slice-inventory.report.json": "bf5f3fd36e1943e0dc42bafb2ed195fad147bcb3e56a8d208d7f01a3641829de",
     "coverage/xyzac-trt-startup.report.json": "56e040b645bcefc3d6c57244cb2d3aba16f421ff5137089d9c3336970dfd968b",
     "coverage/xyzac-trt-threejs.report.json": "5172d7118c555fca5f92bcb443b9c259ea0225346482558d4c33ef8a4f8da5cb",
-    "coverage/xyzac-trt-tool-preview.report.json": "1980f3dfad0471bdef5025aec230af5c5ba477ebd5ecccb9ada732d435465efd",
+    "coverage/xyzac-trt-tool-preview.report.json": "40d6d38a55a8d9b86601a0dc80a3edbbcdfd371207c058f944e64e979cce8c43",
     "coverage/xyzac-trt-trace-parity.report.json": "6c6b3500bc1189ff68513b74f0e5144879c3af7641349cb61737191303b76950",
-    "coverage/xyzac-trt-wasm-authority-audit.report.json": "57af1a779dc5d48b40b4a8576b7949aecaab2fd2eeaae7dfbbab35c06a254102",
+    "coverage/xyzac-trt-wasm-authority-audit.report.json": "3640d6d96e8152c70fde190491bc30586ef27498dbd5079278e402ee4fb0bfc4",
     "coverage/xyzac-trt-workflow.report.json": "9d0ed087b17ec14c906f4268d2d616dbc3800da03f731376b2ef9ae44ca5c6e7"
   },
-  "report_sha256": "03d305c986a03aaaf6e04833b8e0d4095d840f89741582cd50be307f1aeed73c",
+  "report_sha256": "d940a5cda017837ea4c71885c698327115d8404e77bfbebb828079b805e80f66",
   "schema": "xyzac-trt-web-wasm-parity-report.v1",
   "source_coverage": {
     "axis_keyboard": 10,
diff --git a/web/react/src/App.tsx b/web/react/src/App.tsx
index 8ad9608..71ef5ea 100644
--- a/web/react/src/App.tsx
+++ b/web/react/src/App.tsx
@@ -87,15 +87,19 @@ function DroView({ axes, state, coordType, displayType, metric, setCoordType, se
   return <section className="dro-view" data-axis-feature="AXIS-VIEW-04" role="tabpanel" aria-label="DRO"><div className="dro-mode-row"><strong>Position</strong><label>Coordinate<select data-axis-feature="AXIS-VIEW-18" value={coordType} onChange={(event) => setCoordType(event.target.value as "machine" | "relative")}><option value="machine">Machine</option><option value="relative">Relative</option></select></label><label>Display<select data-axis-feature="AXIS-VIEW-17" value={displayType} onChange={(event) => setDisplayType(event.target.value as "actual" | "commanded")}><option value="actual">Actual</option><option value="commanded">Commanded</option></select></label><label>Units<select data-axis-feature="AXIS-VIEW-02" value={metric ? "mm" : "inch"} onChange={(event) => setMetric(event.target.value === "mm")}><option value="mm">mm</option><option value="inch">inch</option></select></label></div><div className="dro-column-headings"><span /><span>Displayed</span><span>Actual</span><span>Relative</span></div><div className="dro-table">{labels.map((label, index) => { const actual = Number(axes[index] ?? 0); const target = Number(commanded[index] ?? actual); const relativeValue = Number(relative[index] ?? actual); const displayed = displayType === "commanded" ? target : actual; return <div className="dro-row" key={label}><strong>{label}</strong><output>{format(coordType === "relative" ? relativeValue : displayed, index)}</output><output>{format(actual, index)}</output><output>{format(relativeValue, index)}</output></div>; })}</div><div className="dro-footer"><span>Units: <b>{metric ? "mm" : "inch"}</b> / deg</span><span>{coordType} / {displayType}</span><span>Tick: {state.tick}</span><span>Hash: {state.snapshot?.state_hash?.slice(0, 12) || "-"}</span></div></section>;
 }
 
-function ProgramPane({ text, setText, activeGcodes, executionTrace, onLoad, onRun, onStep, onOpenFile, canLoad, canRun, canStep, currentLine, executionLine, executionLineText, diagnostic }: { text: string; setText: (text: string) => void; activeGcodes: string; executionTrace: Array<{ line: number; text: string; program_status?: string | null }>; onLoad: () => void; onRun: () => void; onStep: () => void; onOpenFile: () => void; canLoad: boolean; canRun: boolean; canStep: boolean; currentLine: number | null; executionLine: number | null; executionLineText: string; diagnostic: string | null }) {
+function ProgramPane({ text, setText, activeGcodes, executionTrace, programStatus, onLoad, onRun, onStep, onOpenFile, canLoad, canRun, canStep, currentLine, executionLine, executionLineText, diagnostic }: { text: string; setText: (text: string) => void; activeGcodes: string; executionTrace: Array<{ line: number; text: string; program_status?: string | null }>; programStatus: string; onLoad: () => void; onRun: () => void; onStep: () => void; onOpenFile: () => void; canLoad: boolean; canRun: boolean; canStep: boolean; currentLine: number | null; executionLine: number | null; executionLineText: string; diagnostic: string | null }) {
   const lines = text.split("\n");
-  const mainLine = currentLine && currentLine > 0 && currentLine <= lines.length ? currentLine : null;
+  const executing = ["running", "paused"].includes(programStatus.toLowerCase());
+  const mainLine = executing && currentLine && currentLine > 0 && currentLine <= lines.length ? currentLine : null;
+  const executedLines = new Set(executionTrace.map((entry) => entry.line));
+  const editorRef = useRef<HTMLTextAreaElement>(null);
+  const highlightsRef = useRef<HTMLDivElement>(null);
   const traceRef = useRef<HTMLOListElement>(null);
   useEffect(() => {
     const node = traceRef.current;
     if (node) node.scrollTop = node.scrollHeight;
   }, [executionTrace]);
-  return <section className="axis-program-pane" data-axis-feature="AXIS-UI-07" aria-label="G-code program"><div className="program-editor-wrap"><div className="program-gutter" aria-label="G-code line numbers">{lines.map((_, index) => <span key={index} className={index + 1 === mainLine ? "current-line" : ""} aria-current={index + 1 === mainLine ? "true" : undefined}>{index + 1}</span>)}</div><textarea id="axis-program" data-axis-feature="AXIS-EDIT-01" value={text} onChange={(event) => setText(event.target.value)} spellCheck={false} aria-invalid={Boolean(diagnostic)} aria-label="G-code program" /></div><div className="program-execution-line" role="status" aria-label="Currently executing G-code"><span>{executionLine ? `Executing source line ${executionLine}` : "Execution idle"}</span><code>{executionLineText || "-"}</code></div><div className="program-execution-trace" role="log" aria-label="G-code execution trace" aria-live="polite"><strong>Execution trace</strong><ol ref={traceRef}>{executionTrace.slice(-8).map((entry, index) => <li key={`${entry.line}-${index}`}><span>L{entry.line}</span><code>{entry.text || "-"}</code></li>)}</ol></div><aside className="program-side"><div className="program-actions"><TextButton feature="AXIS-EDIT-01" onClick={onOpenFile}>Open file</TextButton><TextButton feature="AXIS-EDIT-01" onClick={onLoad} disabled={!canLoad}>Load</TextButton><TextButton feature="AXIS-CTRL-02" onClick={onRun} disabled={!canRun}>Run</TextButton><TextButton feature="AXIS-CTRL-02" onClick={onStep} disabled={!canStep}>Step</TextButton></div><label className="active-gcodes-label">Active G-Codes:<textarea data-axis-feature="AXIS-UI-07" readOnly value={activeGcodes} aria-label="Active G-Codes" /></label>{diagnostic && <output className="program-diagnostic" role="alert" data-axis-feature="AXIS-EDIT-01">{diagnostic}</output>}</aside></section>;
+  return <section className="axis-program-pane" data-axis-feature="AXIS-UI-07" aria-label="G-code program"><div className="program-editor-wrap"><div className="program-gutter" aria-label="G-code line numbers">{lines.map((_, index) => { const line = index + 1; const className = line === mainLine ? "current-line" : executedLines.has(line) ? "completed-line" : ""; return <span key={index} className={className} aria-current={line === mainLine ? "true" : undefined}>{line}</span>; })}</div><div className="program-editor-input"><div ref={highlightsRef} className="program-line-highlights" aria-hidden="true">{lines.map((_, index) => { const line = index + 1; const className = line === mainLine ? "current-line" : executedLines.has(line) ? "completed-line" : ""; return <span key={index} className={className} />; })}</div><textarea ref={editorRef} id="axis-program" data-axis-feature="AXIS-EDIT-01" value={text} onChange={(event) => setText(event.target.value)} onScroll={() => { if (editorRef.current && highlightsRef.current) { highlightsRef.current.scrollTop = editorRef.current.scrollTop; highlightsRef.current.scrollLeft = editorRef.current.scrollLeft; } }} spellCheck={false} aria-invalid={Boolean(diagnostic)} aria-label="G-code program" /></div></div><div className="program-execution-line" role="status" aria-label="Currently executing G-code"><span>{executionLine ? `Executing source line ${executionLine}` : "Execution idle"}</span><code>{executionLineText || "-"}</code></div><div className="program-execution-trace" role="log" aria-label="G-code execution trace" aria-live="polite"><strong>Execution trace</strong><ol ref={traceRef}>{executionTrace.slice(-8).map((entry, index, entries) => { const isCurrent = executing && index === entries.length - 1; return <li key={`${entry.line}-${index}`} className={isCurrent ? "executing-line" : "completed-line"} aria-current={isCurrent ? "true" : undefined}><span>L{entry.line}</span><code>{entry.text || "-"}</code></li>; })}</ol></div><aside className="program-side"><div className="program-actions"><TextButton feature="AXIS-EDIT-01" onClick={onOpenFile}>Open file</TextButton><TextButton feature="AXIS-EDIT-01" onClick={onLoad} disabled={!canLoad}>Load</TextButton><TextButton feature="AXIS-CTRL-02" onClick={onRun} disabled={!canRun}>Run</TextButton><TextButton feature="AXIS-CTRL-02" onClick={onStep} disabled={!canStep}>Step</TextButton></div><label className="active-gcodes-label">Active G-Codes:<textarea data-axis-feature="AXIS-UI-07" readOnly value={activeGcodes} aria-label="Active G-Codes" /></label>{diagnostic && <output className="program-diagnostic" role="alert" data-axis-feature="AXIS-EDIT-01">{diagnostic}</output>}</aside></section>;
 }
 
 function DiagnosticsPanel({ state, gates }: { state: typeof INITIAL_STATE; gates: Record<string, { enabled: boolean; reason: string }> }) {
@@ -240,7 +244,7 @@ export function App() {
     <XyzacTrtPanel view={xyzacView} command={xyzacCommand} />
     <section className="axis-top-pane" data-axis-feature="AXIS-UI-06"><div className="axis-notebook left-notebook" data-axis-feature="AXIS-UI-06"><div className="notebook-tabs" role="tablist" aria-label="Manual, MDI and diagnostics controls"><button id="axis-tab-manual" type="button" role="tab" aria-controls="axis-panel-manual" aria-selected={leftTab === "manual"} className={leftTab === "manual" ? "active" : ""} onClick={enterManualMode}>Manual Control [F3]</button><button id="axis-tab-mdi" type="button" role="tab" aria-controls="axis-panel-mdi" aria-selected={leftTab === "mdi"} className={leftTab === "mdi" ? "active" : ""} onClick={() => setLeftTab("mdi")}>MDI [F5]</button><button id="axis-tab-diagnostics" type="button" role="tab" aria-controls="axis-panel-diagnostics" aria-selected={leftTab === "diagnostics"} className={leftTab === "diagnostics" ? "active" : ""} onClick={() => setLeftTab("diagnostics")}>Diagnostics</button></div><div id="axis-panel-manual" role="tabpanel" aria-labelledby="axis-tab-manual" hidden={leftTab !== "manual"}><ManualControl action={execute} ready={gates.jog.enabled} canHome={gates.home.enabled} onHomeAll={homeAll} selectedAxis={selectedAxis} setSelectedAxis={setSelectedAxis} spindleOn={spindleOn} coolant={coolant} onSpindle={onSpindle} onCoolant={onCoolant} devices={state.devices ?? {}} /></div><div id="axis-panel-mdi" role="tabpanel" aria-labelledby="axis-tab-mdi" hidden={leftTab !== "mdi"}><MdiControl action={execute} ready={gates.mdi.enabled} /></div><div id="axis-panel-diagnostics" role="tabpanel" aria-labelledby="axis-tab-diagnostics" hidden={leftTab !== "diagnostics"}><DiagnosticsPanel state={state} gates={gates} /><XyzacDiagnostics view={xyzacView} operations={operationTrace} alarms={state.alarms} error={state.error} /></div></div><div className="axis-notebook right-notebook" data-axis-feature="AXIS-UI-06"><div className="notebook-tabs" role="tablist" aria-label="Preview and DRO"><button id="axis-tab-preview" type="button" role="tab" aria-controls="axis-panel-preview" aria-selected={rightTab === "preview"} className={rightTab === "preview" ? "active" : ""} onClick={() => setRightTab("preview")}>Preview</button><button id="axis-tab-dro" type="button" role="tab" aria-controls="axis-panel-dro" aria-selected={rightTab === "dro"} className={rightTab === "dro" ? "active" : ""} onClick={() => setRightTab("dro")}>DRO</button></div><div id="axis-panel-preview" role="tabpanel" aria-labelledby="axis-tab-preview" className="axis-preview" hidden={rightTab !== "preview"}><XyzacToolPreviewFromSnapshot snapshot={state.snapshot} view={view} zoom={zoom} rotateMode={rotateMode} showPath={layers.path} showLive={layers.live} showLimits={layers.limits} showVelocity={layers.velocity} showOffsets={layers.offsets} showExtents={layers.extents} /></div><div id="axis-panel-dro" role="tabpanel" aria-labelledby="axis-tab-dro" hidden={rightTab !== "dro"}><DroView axes={axes} state={state} coordType={coordType} displayType={displayType} metric={metric} setCoordType={setCoordType} setDisplayType={setDisplayType} setMetric={setMetric} /></div></div></section>
     <section className="axis-metrics" data-axis-feature="AXIS-VIEW-03"><div className="axis-slider"><label>Jog Speed:<output>50%</output><input type="range" min="6" max="100" defaultValue="50" /></label><label>Feed Override:<output>{Math.round((state.snapshot?.overrides?.feed ?? 1) * 100)}%</output><input type="range" min="0" max="120" defaultValue="100" onChange={(event) => execute("SET_OVERRIDE", { feed: Number(event.target.value) / 100 })} /></label><label>Spindle Override:<output>{Math.round((state.snapshot?.overrides?.spindle?.[0] ?? 1) * 100)}%</output><input type="range" min="0" max="120" defaultValue="100" /></label></div><div className="axis-layer-controls" aria-label="Preview layers">{(["path", "live", "limits", "velocity", "offsets", "extents"] as const).map((layer) => <label key={layer}><input type="checkbox" data-axis-feature="AXIS-VIEW-03" checked={layers[layer]} onChange={(event) => setLayers((current) => ({ ...current, [layer]: event.target.checked }))} /> {layer}</label>)}</div></section>
-    <XyzacProgramPane status={String(state.program?.program_status ?? "idle")} currentLine={executionLine} sourceHash={String(state.program?.source_hash ?? "")}><ProgramPane text={programText} setText={setProgramText} activeGcodes={activeGcodes} executionTrace={state.executionTrace} onOpenFile={openProgramFile} onLoad={() => { setPlotCleared(false); execute("PROGRAM_LOAD", { source: programText, path: PROGRAM_PATH }); }} onRun={runProgram} onStep={() => execute("PROGRAM_STEP")} canLoad={gates.load.enabled} canRun={gates.run.enabled} canStep={gates.step.enabled} currentLine={currentLine} executionLine={executionLine} executionLineText={executionLineText} diagnostic={state.error?.code ?? null} /></XyzacProgramPane>
+    <XyzacProgramPane status={String(state.program?.program_status ?? "idle")} currentLine={executionLine} sourceHash={String(state.program?.source_hash ?? "")}><ProgramPane text={programText} setText={setProgramText} activeGcodes={activeGcodes} executionTrace={state.executionTrace} programStatus={String(state.program?.program_status ?? "idle")} onOpenFile={openProgramFile} onLoad={() => { setPlotCleared(false); execute("PROGRAM_LOAD", { source: programText, path: PROGRAM_PATH }); }} onRun={runProgram} onStep={() => execute("PROGRAM_STEP")} canLoad={gates.load.enabled} canRun={gates.run.enabled} canStep={gates.step.enabled} currentLine={currentLine} executionLine={executionLine} executionLineText={executionLineText} diagnostic={state.error?.code ?? null} /></XyzacProgramPane>
     <input ref={programFileInput} className="visually-hidden-file-input" type="file" accept=".ngc,.nc,.gcode,.tap,text/plain" onChange={onProgramFile} aria-label="Open G-code file" />
     <footer className="axis-info-bar" data-axis-feature="AXIS-UI-07"><span className={`task-state ${state.status}`} data-axis-feature="AXIS-SHELL-01">{taskState}</span><span className="machine-state" data-axis-state-machine={machineState}>Machine {machineState}</span><span className="operation-state" data-axis-state-operation={operationState}>Operation {operationState}</span><span className="tool-state" data-axis-feature="AXIS-UI-07">Tool {toolNumber}</span><span className="position-state" data-axis-feature="AXIS-VIEW-17">{position}</span><span className="footer-status" role="status">{state.error ? `Error: ${state.error.code}` : commandStatus}</span></footer>
   </main>;
diff --git a/web/react/src/store.ts b/web/react/src/store.ts
index d61cdb1..a54a586 100644
--- a/web/react/src/store.ts
+++ b/web/react/src/store.ts
@@ -63,7 +63,8 @@ function projection(result: Record<string, unknown>, message: MessageEnvelope, p
       .map((entry) => ({ line: Number(entry.line), text: String(entry.text ?? ""), program_status: entry.program_status ? String(entry.program_status) : null }))
       .filter((entry) => Number.isSafeInteger(entry.line) && entry.line > 0)
     : [];
-  const executionTrace = trace.length ? [...previous.executionTrace, ...trace].slice(-32) : previous.executionTrace;
+  const resetExecutionTrace = ["PROGRAM_LOAD", "PROGRAM_RESTART"].includes(String(result.command ?? ""));
+  const executionTrace = resetExecutionTrace ? trace.slice(-32) : trace.length ? [...previous.executionTrace, ...trace].slice(-32) : previous.executionTrace;
   const delta = result.motion_sample as { tick?: number; pose?: Record<string, number>; joints?: number[]; active_segment_id?: number; active_progress?: number } | undefined;
   if (!panel && delta && previous.snapshot) {
     const pose = delta.pose ?? {};
diff --git a/web/react/src/styles.css b/web/react/src/styles.css
index 8d52edf..1c03220 100644
--- a/web/react/src/styles.css
+++ b/web/react/src/styles.css
@@ -181,9 +181,15 @@ output { font: 12px ui-monospace, monospace; text-align: right; }
 .program-editor-wrap { display: grid; grid-template-columns: 34px minmax(0, 1fr); min-width: 0; min-height: 0; }
 .program-gutter { display: flex; flex-direction: column; align-items: end; padding: 6px 6px 6px 0; overflow: hidden; border-right: 1px solid #c2c2c2; color: #888; background: #e4e4e4; font: 12px/1.45 ui-monospace, monospace; user-select: none; }
 .program-gutter span { height: 17px; }
-.program-gutter span.current-line { color: #174d84; background: #c8d7e8; font-weight: 700; }
-.program-editor-wrap textarea { width: 100%; height: 100%; min-height: 180px; padding: 6px 8px; resize: none; border: 0; outline: none; background: #fff; color: #111; font: 12px/1.45 ui-monospace, monospace; tab-size: 4; }
-.program-execution-line { display: grid; grid-column: 1; grid-row: 2; grid-template-columns: max-content minmax(0, 1fr); align-items: baseline; gap: 10px; min-width: 0; padding: 5px 8px; border-top: 1px solid #9aa8b4; border-bottom: 1px solid #9aa8b4; background: #e9f1f8; color: #173b5f; font: 12px/1.35 ui-monospace, monospace; }
+.program-gutter span.current-line { color: #5a4100; background: #ffe066; font-weight: 700; }
+.program-gutter span.completed-line { color: #666; background: #e6e6e6; }
+.program-editor-input { position: relative; min-width: 0; min-height: 0; overflow: hidden; background: #fff; }
+.program-line-highlights { position: absolute; inset: 0; z-index: 0; padding: 6px 8px; overflow: hidden; pointer-events: none; font: 12px/1.45 ui-monospace, monospace; }
+.program-line-highlights span { display: block; height: 17px; margin: 0 -8px; }
+.program-line-highlights span.completed-line { background: #eeeeee; }
+.program-line-highlights span.current-line { background: #ffe066; }
+.program-editor-input textarea { position: relative; z-index: 1; width: 100%; height: 100%; min-height: 180px; padding: 6px 8px; resize: none; border: 0; outline: none; background: transparent; color: #111; font: 12px/1.45 ui-monospace, monospace; tab-size: 4; }
+.program-execution-line { display: grid; grid-column: 1; grid-row: 2; grid-template-columns: max-content minmax(0, 1fr); align-items: baseline; gap: 10px; min-width: 0; padding: 5px 8px; border-top: 1px solid #9aa8b4; border-bottom: 1px solid #9aa8b4; background: #ffe066; color: #3f2d00; font: 12px/1.35 ui-monospace, monospace; }
 .program-execution-line span { font-weight: 700; white-space: nowrap; }
 .program-execution-line code { min-width: 0; overflow: hidden; color: #111; text-overflow: ellipsis; white-space: nowrap; }
 .program-execution-trace { grid-column: 1; grid-row: 3; min-width: 0; padding: 4px 8px; overflow: auto; border-bottom: 1px solid #9aa8b4; background: #f4f7fa; color: #253746; font: 11px/1.3 ui-monospace, monospace; }
@@ -192,6 +198,9 @@ output { font: 12px ui-monospace, monospace; text-align: right; }
 .program-execution-trace li { display: grid; grid-template-columns: 42px minmax(0, 1fr); gap: 8px; min-width: 0; }
 .program-execution-trace li span { color: #174d84; font-weight: 700; }
 .program-execution-trace li code { min-width: 0; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
+.program-execution-trace li.completed-line { padding: 1px 4px; background: #e8e8e8; color: #666; }
+.program-execution-trace li.executing-line { padding: 1px 4px; background: #ffe066; color: #111; font-weight: 700; }
+.program-execution-trace li.executing-line span { color: #6b4b00; }
 .program-side { display: flex; grid-column: 2; grid-row: 1 / span 3; flex-direction: column; gap: 12px; padding: 8px; border-left: 1px solid #aaa; background: #d9d9d9; }
 .program-actions { display: flex; flex-wrap: wrap; gap: 5px; }
 .active-gcodes-label { display: grid; gap: 5px; color: #333; }