diff --git a/frontend/app.js b/frontend/app.js
index e36c946..b99ac24 100644
--- a/frontend/app.js
+++ b/frontend/app.js
@@ -33,7 +33,11 @@ const state = {
   boxStartY: 0,
   boxMoved: false,
   suppressCanvasClick: false,
-  compileDebounceId: null
+  compileDebounceId: null,
+  historyPast: [],
+  historyFuture: [],
+  historyLimit: 80,
+  historyRestoring: false
 };
 
 const el = {
@@ -109,6 +113,8 @@ const el = {
   copyReproBtn: document.getElementById("copyReproBtn"),
   autoLayoutBtn: document.getElementById("autoLayoutBtn"),
   autoTidyBtn: document.getElementById("autoTidyBtn"),
+  undoBtn: document.getElementById("undoBtn"),
+  redoBtn: document.getElementById("redoBtn"),
   renderModeSelect: document.getElementById("renderModeSelect"),
   isolateNetBtn: document.getElementById("isolateNetBtn"),
   isolateComponentBtn: document.getElementById("isolateComponentBtn"),
@@ -128,6 +134,76 @@ function clone(obj) {
   return JSON.parse(JSON.stringify(obj));
 }
 
+function captureHistorySnapshot() {
+  if (!state.model) {
+    return null;
+  }
+  return {
+    model: clone(state.model),
+    selectedRefs: [...state.selectedRefs],
+    selectedNet: state.selectedNet,
+    selectedPin: state.selectedPin ? { ...state.selectedPin, nets: [...(state.selectedPin.nets ?? [])] } : null,
+    isolateNet: Boolean(state.isolateNet),
+    isolateComponent: Boolean(state.isolateComponent)
+  };
+}
+
+function restoreHistorySnapshot(snapshot) {
+  if (!snapshot) {
+    return;
+  }
+  state.model = clone(snapshot.model);
+  setSelectedRefs(snapshot.selectedRefs ?? []);
+  state.selectedNet = snapshot.selectedNet ?? null;
+  state.selectedPin = snapshot.selectedPin ? { ...snapshot.selectedPin } : null;
+  state.isolateNet = Boolean(snapshot.isolateNet);
+  state.isolateComponent = Boolean(snapshot.isolateComponent);
+}
+
+function pushHistory(reason = "edit") {
+  const snap = captureHistorySnapshot();
+  if (!snap) {
+    return;
+  }
+  state.historyPast.push({ reason, snapshot: snap });
+  if (state.historyPast.length > state.historyLimit) {
+    state.historyPast.splice(0, state.historyPast.length - state.historyLimit);
+  }
+  state.historyFuture = [];
+}
+
+async function performUndo() {
+  if (!state.historyPast.length || !state.model) {
+    return;
+  }
+  const current = captureHistorySnapshot();
+  const prev = state.historyPast.pop();
+  if (!prev?.snapshot || !current) {
+    return;
+  }
+  state.historyFuture.push({ reason: prev.reason, snapshot: current });
+  state.historyRestoring = true;
+  restoreHistorySnapshot(prev.snapshot);
+  await compileModel(state.model, { keepView: true, source: "undo" });
+  state.historyRestoring = false;
+}
+
+async function performRedo() {
+  if (!state.historyFuture.length || !state.model) {
+    return;
+  }
+  const current = captureHistorySnapshot();
+  const next = state.historyFuture.pop();
+  if (!next?.snapshot || !current) {
+    return;
+  }
+  state.historyPast.push({ reason: next.reason, snapshot: current });
+  state.historyRestoring = true;
+  restoreHistorySnapshot(next.snapshot);
+  await compileModel(state.model, { keepView: true, source: "redo" });
+  state.historyRestoring = false;
+}
+
 function hasSelectionModifier(evt) {
   return Boolean(evt?.ctrlKey || evt?.metaKey || evt?.shiftKey);
 }
@@ -945,12 +1021,14 @@ function focusIssue(issueId) {
     state.selectedNet = target.net;
     setSelectedRefs([]);
     state.selectedPin = null;
+    state.isolateComponent = false;
     renderAll();
     flashElements(`[data-net="${target.net}"], [data-net-label="${target.net}"], [data-net-junction="${target.net}"], [data-net-tie="${target.net}"]`);
   } else if (target.type === "component" && target.ref) {
     selectSingleRef(target.ref);
     state.selectedNet = null;
     state.selectedPin = null;
+    state.isolateNet = false;
     renderAll();
     flashElements(`[data-ref="${target.ref}"]`);
   } else if (target.type === "pin" && target.ref && target.pin) {
@@ -961,6 +1039,7 @@ function focusIssue(issueId) {
       pin: target.pin,
       nets: []
     };
+    state.isolateNet = false;
     renderAll();
     flashElements(`[data-pin-ref="${target.ref}"][data-pin-name="${target.pin}"]`);
   }
@@ -990,6 +1069,15 @@ function bindSvgInteractions() {
 
   svg.querySelectorAll("[data-ref]").forEach((node) => {
     node.addEventListener("pointerdown", (evt) => {
+      if (
+        evt.target.closest("[data-pin-ref]") ||
+        evt.target.closest("[data-net]") ||
+        evt.target.closest("[data-net-label]") ||
+        evt.target.closest("[data-net-junction]") ||
+        evt.target.closest("[data-net-tie]")
+      ) {
+        return;
+      }
       evt.stopPropagation();
       evt.preventDefault();
       const ref = node.getAttribute("data-ref");
@@ -1001,6 +1089,7 @@ function bindSvgInteractions() {
         toggleSelectedRef(ref);
         state.selectedNet = null;
         state.selectedPin = null;
+        state.isolateNet = false;
         renderAll();
         return;
       }
@@ -1010,6 +1099,7 @@ function bindSvgInteractions() {
       }
       state.selectedNet = null;
       state.selectedPin = null;
+      state.isolateNet = false;
       renderInstances();
       renderNets();
       renderSelected();
@@ -1061,6 +1151,7 @@ function bindSvgInteractions() {
       state.selectedNet = net;
       setSelectedRefs([]);
       state.selectedPin = null;
+      state.isolateComponent = false;
       renderAll();
     });
   });
@@ -1090,6 +1181,7 @@ function bindSvgInteractions() {
       state.selectedPin = { ref, pin, nets };
       selectSingleRef(ref);
       state.selectedNet = null;
+      state.isolateNet = false;
       renderAll();
     });
   });
@@ -1117,6 +1209,8 @@ function renderAll() {
 
   el.isolateNetBtn.classList.toggle("activeChip", state.isolateNet);
   el.isolateComponentBtn.classList.toggle("activeChip", state.isolateComponent);
+  el.undoBtn.disabled = state.historyPast.length === 0;
+  el.redoBtn.disabled = state.historyFuture.length === 0;
 }
 
 async function compileModel(model, opts = {}) {
@@ -1550,6 +1644,7 @@ async function runLayoutAction(path) {
     return;
   }
 
+  pushHistory(path.includes("auto") ? "auto-layout" : "auto-tidy");
   setStatus(path.includes("auto") ? "Auto layout..." : "Auto tidy...");
   try {
     const out = await apiPost(path, {
@@ -1579,6 +1674,9 @@ async function loadSample() {
   }
 
   const model = await res.json();
+  if (state.model) {
+    pushHistory("load-sample");
+  }
   setSelectedRefs([]);
   state.selectedNet = null;
   state.selectedPin = null;
@@ -1602,6 +1700,7 @@ function setupEvents() {
     }
     state.selectedNet = null;
     state.selectedPin = null;
+    state.isolateNet = false;
     renderAll();
   });
 
@@ -1613,6 +1712,7 @@ function setupEvents() {
     state.selectedNet = item.getAttribute("data-net-item");
     setSelectedRefs([]);
     state.selectedPin = null;
+    state.isolateComponent = false;
     renderAll();
   });
 
@@ -1644,6 +1744,7 @@ function setupEvents() {
       return;
     }
 
+    pushHistory("component-edit");
     const oldRef = inst.ref;
     updateInstance(oldRef, {
       ref: nextRef,
@@ -1687,6 +1788,7 @@ function setupEvents() {
     if (!inst) {
       return;
     }
+    pushHistory("rotate");
     const current = Number(inst.placement.rotation ?? 0);
     inst.placement.rotation = ((Math.round(current / 90) * 90 + 90) % 360 + 360) % 360;
     inst.placement.locked = true;
@@ -1700,6 +1802,7 @@ function setupEvents() {
       return;
     }
     const { ref, pin } = state.selectedPin;
+    pushHistory("pin-ui");
     if (!setPinUi(ref, pin, { show_net_label: el.showPinNetLabelInput.checked })) {
       return;
     }
@@ -1742,6 +1845,7 @@ function setupEvents() {
       return;
     }
 
+    pushHistory("pin-props");
     const beforeName = sym.pins[idx].name;
     sym.pins[idx] = {
       ...sym.pins[idx],
@@ -1766,6 +1870,7 @@ function setupEvents() {
       el.jsonFeedback.textContent = "Choose a net first.";
       return;
     }
+    pushHistory("connect-pin");
     const out = connectPinToNet(state.selectedPin.ref, state.selectedPin.pin, netName);
     if (!out.ok) {
       el.jsonFeedback.textContent = out.message;
@@ -1782,6 +1887,7 @@ function setupEvents() {
     }
     const name = normalizeNetName(el.newNetNameInput.value || el.newNetNameInput.placeholder || nextAutoNetName());
     const cls = el.newNetClassInput.value;
+    pushHistory("create-net");
     const out = connectPinToNet(state.selectedPin.ref, state.selectedPin.pin, name, { netClass: cls });
     if (!out.ok) {
       el.jsonFeedback.textContent = out.message;
@@ -1799,6 +1905,7 @@ function setupEvents() {
       return;
     }
     const netName = btn.getAttribute("data-disconnect-net");
+    pushHistory("disconnect-pin");
     const out = disconnectPinFromNet(state.selectedPin.ref, state.selectedPin.pin, netName);
     if (!out.ok) {
       el.jsonFeedback.textContent = out.message;
@@ -1812,6 +1919,7 @@ function setupEvents() {
     if (!state.selectedNet) {
       return;
     }
+    pushHistory("net-edit");
     const oldName = state.selectedNet;
     const renamed = renameNet(oldName, el.netNameInput.value);
     if (!renamed.ok) {
@@ -1838,6 +1946,7 @@ function setupEvents() {
       el.jsonFeedback.textContent = "Provide both ref and pin.";
       return;
     }
+    pushHistory("net-node-add");
     const out = connectPinToNet(ref, pin, state.selectedNet);
     if (!out.ok) {
       el.jsonFeedback.textContent = out.message;
@@ -1856,6 +1965,7 @@ function setupEvents() {
     const netName = state.selectedNet;
     const [ref, ...pinParts] = String(btn.getAttribute("data-remove-node")).split(".");
     const pin = pinParts.join(".");
+    pushHistory("net-node-remove");
     const out = disconnectPinFromNet(ref, pin, netName);
     if (!out.ok) {
       el.jsonFeedback.textContent = out.message;
@@ -1933,6 +2043,7 @@ function setupEvents() {
       return;
     }
 
+    pushHistory("symbol-edit");
     for (const entry of parsedPins) {
       if (entry.oldName && entry.oldName !== entry.pin.name) {
         renamePinAcrossSymbolInstances(inst.symbol, entry.oldName, entry.pin.name);
@@ -2154,6 +2265,7 @@ function setupEvents() {
     state.dragMoved = false;
 
     if (wasDragging && moved && state.model) {
+      pushHistory("drag-move");
       for (const [ref, pos] of Object.entries(dragSnapshot ?? {})) {
         const inst = state.model.instances.find((x) => x.ref === ref);
         if (inst) {
@@ -2178,12 +2290,29 @@ function setupEvents() {
   });
 
   window.addEventListener("keydown", (evt) => {
+    const mod = evt.ctrlKey || evt.metaKey;
+    if (mod && evt.key.toLowerCase() === "z") {
+      evt.preventDefault();
+      if (evt.shiftKey) {
+        void performRedo();
+      } else {
+        void performUndo();
+      }
+      return;
+    }
+    if (mod && evt.key.toLowerCase() === "y") {
+      evt.preventDefault();
+      void performRedo();
+      return;
+    }
+
     if (evt.code === "Space") {
       if (isTypingContext(evt.target)) {
         return;
       }
 
       if (state.selectedRefs.length && state.model && !evt.repeat) {
+        pushHistory("rotate-hotkey");
         for (const ref of state.selectedRefs) {
           const inst = state.model.instances.find((x) => x.ref === ref);
           if (!inst) {
@@ -2212,7 +2341,20 @@ function setupEvents() {
       }
     }
     if (evt.code === "Escape") {
-      closeSchemaModal();
+      if (!el.schemaModal.classList.contains("hidden")) {
+        closeSchemaModal();
+        return;
+      }
+      const hadSelection = Boolean(state.selectedRefs.length || state.selectedNet || state.selectedPin);
+      const hadIsolation = Boolean(state.isolateNet || state.isolateComponent);
+      if (hadSelection || hadIsolation) {
+        setSelectedRefs([]);
+        state.selectedNet = null;
+        state.selectedPin = null;
+        state.isolateNet = false;
+        state.isolateComponent = false;
+        renderAll();
+      }
     }
   });
 
@@ -2290,6 +2432,9 @@ function setupEvents() {
     try {
       const parsed = JSON.parse(el.jsonEditor.value);
       const before = state.model ? clone(state.model) : null;
+      if (state.model) {
+        pushHistory("apply-json");
+      }
       el.jsonFeedback.textContent = "Applying JSON...";
       setSelectedRefs([]);
       state.selectedNet = null;
@@ -2303,6 +2448,9 @@ function setupEvents() {
   });
 
   el.newProjectBtn.addEventListener("click", async () => {
+    if (state.model) {
+      pushHistory("new-project");
+    }
     setSelectedRefs([]);
     state.selectedNet = null;
     state.selectedPin = null;
@@ -2319,6 +2467,14 @@ function setupEvents() {
     await runLayoutAction("/layout/tidy");
   });
 
+  el.undoBtn.addEventListener("click", async () => {
+    await performUndo();
+  });
+
+  el.redoBtn.addEventListener("click", async () => {
+    await performRedo();
+  });
+
   el.importBtn.addEventListener("click", () => {
     el.fileInput.click();
   });
@@ -2332,6 +2488,9 @@ function setupEvents() {
     try {
       const content = await file.text();
       const parsed = JSON.parse(content);
+      if (state.model) {
+        pushHistory("import-json");
+      }
       setSelectedRefs([]);
       state.selectedNet = null;
       state.selectedPin = null;
diff --git a/frontend/index.html b/frontend/index.html
index e39c967..1b5e9de 100644
--- a/frontend/index.html
+++ b/frontend/index.html
@@ -19,6 +19,8 @@
         <button id="exportBtn">Export JSON</button>
         <button id="autoLayoutBtn">Auto Layout</button>
         <button id="autoTidyBtn">Auto Tidy</button>
+        <button id="undoBtn" title="Undo (Ctrl/Cmd+Z)">Undo</button>
+        <button id="redoBtn" title="Redo (Ctrl/Cmd+Shift+Z)">Redo</button>
         <label class="inlineSelect">
           Mode
           <select id="renderModeSelect">
diff --git a/frontend/styles.css b/frontend/styles.css
index 69cd1e3..a451a19 100644
--- a/frontend/styles.css
+++ b/frontend/styles.css
@@ -69,6 +69,11 @@ button {
   cursor: pointer;
 }
 
+button:disabled {
+  opacity: 0.5;
+  cursor: not-allowed;
+}
+
 button.primary {
   background: var(--accent);
   color: #fff;