diff --git a/static/ast-parser.js b/static/ast-parser.js
index f785233..d1457b8 100644
--- a/static/ast-parser.js
+++ b/static/ast-parser.js
@@ -7,7 +7,7 @@ function coerce(s) {
     if (s === 'False' || s === 'N' || s === 'off' || s === 'false') return false;
     if (s === '') return s;
     const n = Number(s);
-    if (!isNaN(n) && s.trim() !== '') return n;
+    if (!isNaN(n)) return n;
     return s;
 }
 
diff --git a/static/components/ObjectBasic.js b/static/components/ObjectBasic.js
deleted file mode 100644
index b83eb20..0000000
--- a/static/components/ObjectBasic.js
+++ /dev/null
@@ -1,15 +0,0 @@
-import { h } from 'vue';
-
-// Inline identifier + a few key props — used for list rows.
-export const ObjectBasic = {
-    props: ['label', 'meta'],  // meta: array of {key, value} pairs
-    setup(props) {
-        return () => h('div', { class: 'se-object-label' }, [
-            h('strong', null, props.label),
-            ...(props.meta ?? []).map(({ key, value }) =>
-                h('span', { style: 'color:#888;margin-left:0.5rem;font-size:0.8em' },
-                    `${key}=${value}`)
-            ),
-        ]);
-    },
-};
diff --git a/static/components/ObjectShort.js b/static/components/ObjectShort.js
index 7f11d6c..bcebc58 100644
--- a/static/components/ObjectShort.js
+++ b/static/components/ObjectShort.js
@@ -2,7 +2,7 @@ import { h } from 'vue';
 
 // One-line summary row with a drill-down chevron.
 export const ObjectShort = {
-    props: ['node', 'label', 'typeTag', 'focused', 'hasChildren'],
+    props: ['label', 'typeTag', 'focused', 'hasChildren'],
     emits: ['focus', 'drillDown'],
     setup(props, { emit }) {
         return () => h('li', {
diff --git a/static/components/PaneCP.js b/static/components/PaneCP.js
index b35ac21..fa1a5b4 100644
--- a/static/components/PaneCP.js
+++ b/static/components/PaneCP.js
@@ -49,7 +49,7 @@ export const PaneCP = {
                 props.store.rawScoreText = raw;
                 const patched = patchScore(raw, props.store.scoreModel.instruments, props.store.scoreModel.bars);
                 await putScoreText(patched, props.store.credentials);
-                props.store.synthesisStatus = { frozen: false, progress: 0 };
+                props.store.synthesisStatus = { frozen: false, currently_rendered_notes: 0, notes_in_total: 0 };
             } catch (e) {
                 exportError.value = e.message;
             } finally {
diff --git a/static/components/PaneFO.js b/static/components/PaneFO.js
index a61311e..1954be7 100644
--- a/static/components/PaneFO.js
+++ b/static/components/PaneFO.js
@@ -3,11 +3,9 @@ import { ObjectExtended } from './ObjectExtended.js';
 import { EnvelopeEditor } from './EnvelopeEditor.js';
 import { ShapeEditor } from './ShapeEditor.js';
 import { LinkedInstrumentModal } from './LinkedInstrumentModal.js';
+import { stressorToString } from '../exporter.js';
 
-function stressorToString(s) {
-    if (!s?.groups?.length) return '';
-    return s.groups.map(g => g.join(',')).join(';');
-}
+const H4 = { style: 'margin:0 0 0.5rem' };
 
 function parseStressor(str) {
     const groups = str.split(';').map(seg =>
@@ -27,38 +25,42 @@ function scoreInfoFields(info) {
 
 function instrFields(instr) {
     return [
-        { key: 'name', value: instr.name, editable: false },
-        { key: 'linked', value: instr.isLinked, editable: false, type: 'boolean' },
+        { key: 'name',             value: instr.name,                    editable: false },
+        { key: 'linked',           value: instr.isLinked,                editable: false, type: 'boolean' },
         { key: 'NOT_CHANGED_SINCE', value: instr.notChangedSince ?? '—', editable: false },
     ];
 }
 
 function variationFields(v) {
-    return [
-        { key: 'depends_on', value: v.dependsOn ?? '—', editable: true },
-    ];
+    return [{ key: 'depends_on', value: v.dependsOn ?? '—', editable: true }];
+}
+
+function shapeSection(label, shape, onChange) {
+    if (!shape) return null;
+    return h('div', { style: 'margin-top:0.5rem' }, [
+        h('strong', null, label),
+        h(ShapeEditor, { shape, onChange }),
+    ]);
 }
 
 export const PaneFO = {
     props: ['store'],
     setup(props) {
-        // Pending edit held while the linked-instrument modal is shown.
-        const pendingEdit = ref(null);  // { instr, apply: fn }
+        const pendingEdit = ref(null);  // { instr, undo? }
 
         function focused() {
             const fp = props.store.focusPath;
             return fp.length ? fp[fp.length - 1] : null;
         }
 
-        // Returns a change handler that intercepts the first edit to a linked
-        // instrument and shows the embed-or-discard modal before applying it.
-        // `info` may carry { undo } forwarded from ShapeEditor / EnvelopeEditor.
-        function makeChangeHandler(instr, apply) {
+        // Intercepts the first edit to a linked instrument:
+        // shows embed-or-discard modal before committing. `info.undo`
+        // (forwarded from ShapeEditor/EnvelopeEditor) reverts the mutation on discard.
+        function makeChangeHandler(instr) {
             return (info) => {
                 if (instr.isLinked && !instr.isDirty) {
-                    pendingEdit.value = { instr, apply, undo: info?.undo };
+                    pendingEdit.value = { instr, undo: info?.undo };
                 } else {
-                    apply();
                     instr.isDirty = true;
                     props.store.markDirty();
                 }
@@ -69,7 +71,6 @@ export const PaneFO = {
             instr.name = instr.name.split('/').pop();
             instr.isLinked = false;
             instr.isDirty = true;
-            pendingEdit.value.apply();
             pendingEdit.value = null;
             props.store.markDirty();
         }
@@ -79,6 +80,12 @@ export const PaneFO = {
             pendingEdit.value = null;
         }
 
+        function instrOnChange(instr) {
+            return instr
+                ? makeChangeHandler(instr)
+                : () => props.store.markDirty();
+        }
+
         return () => {
             const node = focused();
             const children = [];
@@ -87,7 +94,7 @@ export const PaneFO = {
                 const model = props.store.scoreModel;
                 if (!model) return h('div', { class: 'se-fo-pane' }, 'No score loaded');
                 return h('div', { class: 'se-fo-pane' }, [
-                    h('h4', { style: 'margin:0 0 0.5rem' }, 'Score'),
+                    h('h4', H4, 'Score'),
                     h(ObjectExtended, {
                         fields: scoreInfoFields(model.info),
                         onChange: ({ key, value }) => {
@@ -101,22 +108,18 @@ export const PaneFO = {
 
             if (node.type === 'instrument') {
                 children.push(
-                    h('h4', { style: 'margin:0 0 0.5rem' }, `Instrument: ${node.name}`),
+                    h('h4', H4, `Instrument: ${node.name}`),
                     h(ObjectExtended, { fields: instrFields(node), onChange: null }),
                 );
             } else if (node.type === 'variation') {
-                // Find the ancestor instrument for linked-instrument gating.
-                const instr = props.store.scoreModel?.instruments.find(
-                    i => i.variations?.includes(node) ||
-                         i.variations?.some(v => v.subvariations?.includes(node))
+                const instr = props.store.scoreModel.instruments.find(
+                    i => i.variations.includes(node) ||
+                         i.variations.some(v => v.subvariations.includes(node))
                 ) ?? null;
-
-                const onChange = instr
-                    ? makeChangeHandler(instr, () => { props.store.markDirty(); })
-                    : () => props.store.markDirty();
+                const onChange = instrOnChange(instr);
 
                 children.push(
-                    h('h4', { style: 'margin:0 0 0.5rem' }, 'Variation'),
+                    h('h4', H4, 'Variation'),
                     h(ObjectExtended, { fields: variationFields(node), onChange: ({ key, value }) => {
                         if (key === 'depends_on') {
                             const old = node.dependsOn;
@@ -131,19 +134,16 @@ export const PaneFO = {
                         : null,
                 );
             } else if (node.type === 'label_spec') {
-                const instr = props.store.scoreModel?.instruments.find(
-                    i => i.variations?.some(v =>
-                        v.labelSpecs?.includes(node) ||
-                        v.subvariations?.some(sv => sv.labelSpecs?.includes(node))
+                const instr = props.store.scoreModel.instruments.find(
+                    i => i.variations.some(v =>
+                        v.labelSpecs.includes(node) ||
+                        v.subvariations.some(sv => sv.labelSpecs.includes(node))
                     )
                 ) ?? null;
-
-                const onChange = instr
-                    ? makeChangeHandler(instr, () => { props.store.markDirty(); })
-                    : () => props.store.markDirty();
+                const onChange = instrOnChange(instr);
 
                 children.push(
-                    h('h4', { style: 'margin:0 0 0.5rem' }, `Label: ${node.label}`),
+                    h('h4', H4, `Label: ${node.label}`),
                     node.basicProperties
                         ? h(EnvelopeEditor, { basicProperties: node.basicProperties, onChange })
                         : null,
@@ -151,35 +151,26 @@ export const PaneFO = {
             } else if (node.type === 'bar') {
                 const markBarDirty = () => { node.isDirty = true; props.store.markDirty(); };
                 children.push(
-                    h('h4', { style: 'margin:0 0 0.5rem' }, `Bar: ${node.id}`),
+                    h('h4', H4, `Bar: ${node.id}`),
                     h(ObjectExtended, {
                         fields: [
-                            { key: 'id', value: node.id, editable: false },
-                            { key: 'beats_per_minute', value: node.tempoLevels ?? '', editable: true, type: 'number' },
-                            { key: 'stress_pattern', value: stressorToString(node.stressor), editable: true },
+                            { key: 'id',               value: node.id,                          editable: false },
+                            { key: 'beats_per_minute', value: node.tempoLevels ?? '',           editable: true, type: 'number' },
+                            { key: 'stress_pattern',   value: stressorToString(node.stressor),  editable: true },
                         ],
                         onChange: ({ key, value }) => {
                             if (key === 'beats_per_minute') node.tempoLevels = isNaN(value) ? null : value;
-                            if (key === 'stress_pattern') node.stressor = parseStressor(value);
+                            if (key === 'stress_pattern')   node.stressor    = parseStressor(value);
                             markBarDirty();
                         },
                     }),
-                    node.upperStressBound ? h('div', { style: 'margin-top:0.5rem' }, [
-                        h('strong', null, 'Upper stress bound'),
-                        h(ShapeEditor, { shape: node.upperStressBound, onChange: markBarDirty }),
-                    ]) : null,
-                    node.lowerStressBound ? h('div', { style: 'margin-top:0.5rem' }, [
-                        h('strong', null, 'Lower stress bound'),
-                        h(ShapeEditor, { shape: node.lowerStressBound, onChange: markBarDirty }),
-                    ]) : null,
-                    node.tempoShape ? h('div', { style: 'margin-top:0.5rem' }, [
-                        h('strong', null, 'Tempo shape'),
-                        h(ShapeEditor, { shape: node.tempoShape, onChange: markBarDirty }),
-                    ]) : null,
+                    shapeSection('Upper stress bound', node.upperStressBound, markBarDirty),
+                    shapeSection('Lower stress bound', node.lowerStressBound, markBarDirty),
+                    shapeSection('Tempo shape',        node.tempoShape,       markBarDirty),
                 );
             } else if (node.type === 'voice') {
                 children.push(
-                    h('h4', { style: 'margin:0 0 0.5rem' }, `Voice: ${node.name}`),
+                    h('h4', H4, `Voice: ${node.name}`),
                     h(ObjectExtended, {
                         fields: [
                             { key: 'articles', value: node.articles.join(', ') || '—', editable: false },
@@ -190,27 +181,26 @@ export const PaneFO = {
                     }),
                 );
             } else if (node.type === 'offset') {
-                const noteStr = n => `${n.pitch}${n.effLength != null ? ' ' + n.effLength : ''}`;
+                const noteStr    = n => `${n.pitch}${n.effLength != null ? ' ' + n.effLength : ''}`;
                 const clusterStr = c => c.notes.length
                     ? c.notes.map(n => `${n.letter ?? ''}${n.shift != null ? n.shift : ''}${n.length != null ? ' ' + n.length : ''}`).join(', ')
                     : `cluster[${c.index}]`;
+                const noteItem = (text, i) => h('li', { class: 'se-object-item', key: i },
+                    h('span', { class: 'se-object-label' }, text));
+
                 children.push(
-                    h('h4', { style: 'margin:0 0 0.5rem' }, `Tick: ${node.tick}`),
+                    h('h4', H4, `Tick: ${node.tick}`),
                     h(ObjectExtended, {
                         fields: [{ key: 'tick', value: node.tick, editable: false }],
                         onChange: null,
                     }),
                     node.stemNotes.length ? h('div', { style: 'margin-top:0.5rem' }, [
                         h('strong', null, 'Stem notes'),
-                        h('ul', { class: 'se-object-list' }, node.stemNotes.map((n, i) =>
-                            h('li', { class: 'se-object-item', key: i },
-                                h('span', { class: 'se-object-label' }, noteStr(n))))),
+                        h('ul', { class: 'se-object-list' }, node.stemNotes.map((n, i) => noteItem(noteStr(n), i))),
                     ]) : null,
                     node.clusters.length ? h('div', { style: 'margin-top:0.5rem' }, [
                         h('strong', null, 'Clusters'),
-                        h('ul', { class: 'se-object-list' }, node.clusters.map((c, i) =>
-                            h('li', { class: 'se-object-item', key: i },
-                                h('span', { class: 'se-object-label' }, clusterStr(c))))),
+                        h('ul', { class: 'se-object-list' }, node.clusters.map((c, i) => noteItem(clusterStr(c), i))),
                     ]) : null,
                 );
             } else {
@@ -223,8 +213,8 @@ export const PaneFO = {
                 pendingEdit.value
                     ? h(LinkedInstrumentModal, {
                         instrumentName: pendingEdit.value.instr.name,
-                        onEmbed: () => embedInstrument(pendingEdit.value.instr),
-                        onDiscard: discardEdit,
+                        onEmbed:    () => embedInstrument(pendingEdit.value.instr),
+                        onDiscard:  discardEdit,
                       })
                     : null,
             ]);
diff --git a/static/components/PaneSubObjects.js b/static/components/PaneSubObjects.js
index 70b0454..ed2b9cc 100644
--- a/static/components/PaneSubObjects.js
+++ b/static/components/PaneSubObjects.js
@@ -1,7 +1,6 @@
 import { h } from 'vue';
 import { ObjectShort } from './ObjectShort.js';
 
-// Shows sub-objects of the currently focused node — variations, bars, voices, etc.
 export const PaneSubObjects = {
     props: ['store', 'onFocusFO'],
     setup(props) {
@@ -15,17 +14,17 @@ export const PaneSubObjects = {
             if (node.type === 'score') {
                 const items = [];
                 if (node.info)
-                    items.push({ kind: 'info', node: node.info, label: node.info.title ?? '(no title)', hasChildren: false });
+                    items.push({ kind: 'info',       node: node.info,  label: node.info.title ?? '(no title)', hasChildren: false });
                 if (node.tuning)
-                    items.push({ kind: 'tuning', node: node.tuning, label: `base ${node.tuning.base ?? '?'}`, hasChildren: false });
+                    items.push({ kind: 'tuning',     node: node.tuning, label: `base ${node.tuning.base ?? '?'}`, hasChildren: false });
                 for (const a of (node.articles ?? []))
-                    items.push({ kind: 'article', node: a, label: a.name, hasChildren: false });
+                    items.push({ kind: 'article',    node: a,  label: a.name,  hasChildren: false });
                 for (const sv of (node.stageVoices ?? []))
-                    items.push({ kind: 'stage', node: sv, label: sv.name, hasChildren: false });
+                    items.push({ kind: 'stage',      node: sv, label: sv.name, hasChildren: false });
                 for (const i of node.instruments)
-                    items.push({ kind: 'instrument', node: i, label: i.name, hasChildren: true });
+                    items.push({ kind: 'instrument', node: i,  label: i.name,  hasChildren: true });
                 for (const b of node.bars)
-                    items.push({ kind: 'bar', node: b, label: b.id, hasChildren: false });
+                    items.push({ kind: 'bar',        node: b,  label: b.id,    hasChildren: Object.keys(b.voices).length > 0 });
                 return items;
             }
             if (node.type === 'instrument') {
@@ -33,12 +32,13 @@ export const PaneSubObjects = {
                     kind: 'variation',
                     node: v,
                     label: `variation ${idx + 1}${v.dependsOn ? ` (${v.dependsOn})` : ''}`,
+                    hasChildren: true,
                 }));
             }
             if (node.type === 'variation') {
                 return [
                     ...node.labelSpecs.map(ls => ({
-                        kind: 'label_spec', node: ls, label: ls.label ?? '(no label)',
+                        kind: 'label_spec', node: ls, label: ls.label ?? '(no label)', hasChildren: false,
                     })),
                     ...node.subvariations.map((sv, idx) => {
                         const dep = sv.dependsOn;
@@ -56,9 +56,7 @@ export const PaneSubObjects = {
             }
             if (node.type === 'voice') {
                 return node.offsets.map((o, idx) => ({
-                    kind: 'offset', node: o,
-                    label: `tick ${o.tick ?? idx}`,
-                    hasChildren: false,
+                    kind: 'offset', node: o, label: `tick ${o.tick ?? idx}`, hasChildren: false,
                 }));
             }
             return [];
@@ -69,20 +67,19 @@ export const PaneSubObjects = {
             const items = subItems(node);
             if (!items.length) return h('div', null, h('em', null, 'No sub-objects'));
 
-            return h('div', null, [
+            return h('div', null,
                 h('ul', { class: 'se-object-list' }, items.map((item, idx) =>
                     h(ObjectShort, {
                         key: idx,
-                        node: item.node,
                         label: item.label,
                         typeTag: item.kind,
                         focused: props.store.focusPath.includes(item.node),
-                        hasChildren: item.hasChildren ?? (item.kind !== 'bar' && item.kind !== 'voice'),
-                        onFocus: () => { props.store.pushFocus(item.node); props.onFocusFO?.(); },
+                        hasChildren: item.hasChildren,
+                        onFocus:    () => { props.store.pushFocus(item.node); props.onFocusFO?.(); },
                         onDrillDown: () => { props.store.pushFocus(item.node); props.onFocusFO?.(); },
                     })
-                )),
-            ]);
+                ))
+            );
         };
     },
 };
diff --git a/static/exporter.js b/static/exporter.js
index 10c0724..aecbec1 100644
--- a/static/exporter.js
+++ b/static/exporter.js
@@ -171,10 +171,15 @@ function patchInstrumentHeader(text, instruments) {
     return result.join('\n');
 }
 
+export function stressorToString(s) {
+    if (!s?.groups?.length) return '';
+    return s.groups.map(g => g.join(',')).join(';');
+}
+
 function patchBarMeta(doc, bar) {
     const props = [];
-    if (bar.stressor?.groups?.length)
-        props.push(`  stress_pattern: ${bar.stressor.groups.map(g => g.join(',')).join(';')}`);
+    const sp = stressorToString(bar.stressor);
+    if (sp) props.push(`  stress_pattern: ${sp}`);
     if (bar.tempoLevels != null)
         props.push(`  beats_per_minute: ${bar.tempoLevels}`);
     const ub = serializeShape(bar.upperStressBound);