diff --git a/patches/@polkadot-api__signers-common.patch b/patches/@polkadot-api__signers-common.patch
new file mode 100644
index 0000000..71e9ac6
--- /dev/null
+++ b/patches/@polkadot-api__signers-common.patch
@@ -0,0 +1,30 @@
+diff --git a/dist/v4.js b/dist/v4.js
+index e8ec50ec7fb5d3dab4f30cbc21fe36d0416f8a9d..cddc959ac2f0f396f17c18680d3d3fb0ca310f46 100644
+--- a/dist/v4.js
++++ b/dist/v4.js
+@@ -21,8 +21,23 @@ const getSignerType = (metadata) => {
+   }
+   if (address.type === "AccountId20" && signature.type === "array" && signature.len === 65 && signature.value.type === "primitive" && signature.value.value === "u8")
+     return [1 /* Ethereum */, []];
+-  if (signature.type !== "enum" || ["Ecdsa", "Ed25519", "Sr25519"].some((x) => !(x in signature.value)))
+-    throw unkownSignerType();
++  // Quantus patch: the variant *names* are not load-bearing.
++  //
++  // Upstream required the signature enum to carry Ecdsa, Ed25519 and Sr25519.
++  // That whitelist exists only to tell the Substrate shape from the Ethereum
++  // one, and the Ethereum arm one line above already decides that structurally —
++  // AccountId20 plus a 65-byte array. Everything below this point is
++  // length-agnostic: createV4Tx concatenates whatever the signer returned and
++  // compact-prefixes the result.
++  //
++  // So this check fired before code that would have worked. Quantus's
++  // DilithiumSignatureScheme carries Dilithium87 and Dilithium65, and the
++  // metadata said so — getSignerType read the type out of the metadata and then
++  // threw the answer away in favour of three hardcoded names. Asking the runtime
++  // and then not believing it is the trap this whole port exists to avoid.
++  //
++  // See quantus/papi-console#1.
++  if (signature.type !== "enum") throw unkownSignerType();
+   if (address.type === "enum") {
+     const id = address.value["Id"];
+     if (id.type === "lookupEntry" && id.value.type === "AccountId32")
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 5df8142..7693437 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -5,6 +5,7 @@ settings:
   excludeLinksFromLockfile: false
 
 patchedDependencies:
+  '@polkadot-api/signers-common': 365a34617de2ae3ad2f7e009f7f3e20e0078448fbfc93c395d323f0e21b75d37
   react18-json-view: 962696fac5fe7ad3e94fd36dad07521c6c3eafd52f219ab335d52438387f6b66
 
 importers:
@@ -46,7 +47,7 @@ importers:
         version: 0.4.2(react-dom@19.2.8(react@19.2.8))(react@19.2.8)
       '@polkadot-api/signers-common':
         specifier: ^0.3.1
-        version: 0.3.1(rxjs@7.8.2)
+        version: 0.3.1(patch_hash=365a34617de2ae3ad2f7e009f7f3e20e0078448fbfc93c395d323f0e21b75d37)(rxjs@7.8.2)
       '@polkadot-api/substrate-bindings':
         specifier: ^0.21.1
         version: 0.21.1
@@ -5022,7 +5023,7 @@ snapshots:
       '@noble/hashes': 2.4.0
       '@paraspell/descriptors': 14.3.4(polkadot-api@3.1.0(esbuild@0.28.1)(rxjs@7.8.2))
       '@paraspell/sdk-core': 14.3.4(typescript@7.0.2)(zod@3.25.76)
-      '@polkadot-api/signers-common': 0.3.1(rxjs@7.8.2)
+      '@polkadot-api/signers-common': 0.3.1(patch_hash=365a34617de2ae3ad2f7e009f7f3e20e0078448fbfc93c395d323f0e21b75d37)(rxjs@7.8.2)
       '@polkadot-api/substrate-bindings': 0.21.1
       '@polkadot-labs/hdkd': 0.0.31
       '@polkadot-labs/hdkd-helpers': 0.0.33
@@ -5190,7 +5191,7 @@ snapshots:
     dependencies:
       '@ledgerhq/hw-transport': 6.35.5
       '@polkadot-api/merkleize-metadata': 1.3.0
-      '@polkadot-api/signers-common': 0.3.0(rxjs@7.8.2)
+      '@polkadot-api/signers-common': 0.3.0(patch_hash=365a34617de2ae3ad2f7e009f7f3e20e0078448fbfc93c395d323f0e21b75d37)(rxjs@7.8.2)
       '@polkadot-api/substrate-bindings': 0.21.0
       '@polkadot-api/tx-creator': 0.2.0(rxjs@7.8.2)
       '@polkadot-api/utils': 0.4.0
@@ -5216,7 +5217,7 @@ snapshots:
   '@polkadot-api/meta-signers@0.3.0':
     dependencies:
       '@polkadot-api/metadata-builders': 0.15.0
-      '@polkadot-api/signers-common': 0.3.0(rxjs@7.8.2)
+      '@polkadot-api/signers-common': 0.3.0(patch_hash=365a34617de2ae3ad2f7e009f7f3e20e0078448fbfc93c395d323f0e21b75d37)(rxjs@7.8.2)
       '@polkadot-api/substrate-bindings': 0.21.0
       '@polkadot-api/tx-creator': 0.2.0(rxjs@7.8.2)
       '@polkadot-api/utils': 0.4.0
@@ -5276,7 +5277,7 @@ snapshots:
   '@polkadot-api/pjs-signer@0.8.0(rxjs@7.8.2)':
     dependencies:
       '@polkadot-api/metadata-builders': 0.15.0
-      '@polkadot-api/signers-common': 0.3.0(rxjs@7.8.2)
+      '@polkadot-api/signers-common': 0.3.0(patch_hash=365a34617de2ae3ad2f7e009f7f3e20e0078448fbfc93c395d323f0e21b75d37)(rxjs@7.8.2)
       '@polkadot-api/substrate-bindings': 0.21.0
       '@polkadot-api/tx-creator': 0.2.0(rxjs@7.8.2)
       '@polkadot-api/utils': 0.4.0
@@ -5286,7 +5287,7 @@ snapshots:
   '@polkadot-api/pjs-signer@0.8.1(rxjs@7.8.2)':
     dependencies:
       '@polkadot-api/metadata-builders': 0.15.1
-      '@polkadot-api/signers-common': 0.3.1(rxjs@7.8.2)
+      '@polkadot-api/signers-common': 0.3.1(patch_hash=365a34617de2ae3ad2f7e009f7f3e20e0078448fbfc93c395d323f0e21b75d37)(rxjs@7.8.2)
       '@polkadot-api/substrate-bindings': 0.21.1
       '@polkadot-api/tx-creator': 0.2.0(rxjs@7.8.2)
       '@polkadot-api/utils': 0.4.0
@@ -5302,7 +5303,7 @@ snapshots:
       '@noble/hashes': 2.4.0
       '@polkadot-api/merkleize-metadata': 1.3.0
       '@polkadot-api/metadata-builders': 0.15.0
-      '@polkadot-api/signers-common': 0.3.0(rxjs@7.8.2)
+      '@polkadot-api/signers-common': 0.3.0(patch_hash=365a34617de2ae3ad2f7e009f7f3e20e0078448fbfc93c395d323f0e21b75d37)(rxjs@7.8.2)
       '@polkadot-api/substrate-bindings': 0.21.0
       '@polkadot-api/tx-creator': 0.2.0(rxjs@7.8.2)
       '@polkadot-api/utils': 0.4.0
@@ -5313,7 +5314,7 @@ snapshots:
       '@noble/hashes': 2.4.0
       '@polkadot-api/merkleize-metadata': 1.3.1
       '@polkadot-api/metadata-builders': 0.15.1
-      '@polkadot-api/signers-common': 0.3.1(rxjs@7.8.2)
+      '@polkadot-api/signers-common': 0.3.1(patch_hash=365a34617de2ae3ad2f7e009f7f3e20e0078448fbfc93c395d323f0e21b75d37)(rxjs@7.8.2)
       '@polkadot-api/substrate-bindings': 0.21.1
       '@polkadot-api/tx-creator': 0.2.0(rxjs@7.8.2)
       '@polkadot-api/utils': 0.4.0
@@ -5335,7 +5336,7 @@ snapshots:
       react: 19.2.8
       react-dom: 19.2.8(react@19.2.8)
 
-  '@polkadot-api/signers-common@0.3.0(rxjs@7.8.2)':
+  '@polkadot-api/signers-common@0.3.0(patch_hash=365a34617de2ae3ad2f7e009f7f3e20e0078448fbfc93c395d323f0e21b75d37)(rxjs@7.8.2)':
     dependencies:
       '@polkadot-api/metadata-builders': 0.15.0
       '@polkadot-api/substrate-bindings': 0.21.0
@@ -5343,7 +5344,7 @@ snapshots:
       '@polkadot-api/utils': 0.4.0
       rxjs: 7.8.2
 
-  '@polkadot-api/signers-common@0.3.1(rxjs@7.8.2)':
+  '@polkadot-api/signers-common@0.3.1(patch_hash=365a34617de2ae3ad2f7e009f7f3e20e0078448fbfc93c395d323f0e21b75d37)(rxjs@7.8.2)':
     dependencies:
       '@polkadot-api/metadata-builders': 0.15.1
       '@polkadot-api/substrate-bindings': 0.21.1
@@ -5414,7 +5415,7 @@ snapshots:
     dependencies:
       '@polkadot-api/merkleize-metadata': 1.3.0
       '@polkadot-api/metadata-builders': 0.15.0
-      '@polkadot-api/signers-common': 0.3.0(rxjs@7.8.2)
+      '@polkadot-api/signers-common': 0.3.0(patch_hash=365a34617de2ae3ad2f7e009f7f3e20e0078448fbfc93c395d323f0e21b75d37)(rxjs@7.8.2)
       '@polkadot-api/substrate-bindings': 0.21.0
       '@polkadot-api/utils': 0.4.0
     transitivePeerDependencies:
@@ -5424,7 +5425,7 @@ snapshots:
     dependencies:
       '@polkadot-api/merkleize-metadata': 1.3.1
       '@polkadot-api/metadata-builders': 0.15.1
-      '@polkadot-api/signers-common': 0.3.1(rxjs@7.8.2)
+      '@polkadot-api/signers-common': 0.3.1(patch_hash=365a34617de2ae3ad2f7e009f7f3e20e0078448fbfc93c395d323f0e21b75d37)(rxjs@7.8.2)
       '@polkadot-api/substrate-bindings': 0.21.1
       '@polkadot-api/utils': 0.4.0
     transitivePeerDependencies:
@@ -5761,7 +5762,7 @@ snapshots:
 
   '@polkahub/plugin@0.9.1(@react-rxjs/core@0.10.8(react@19.2.8)(rxjs@7.8.2))(esbuild@0.28.1)(react@19.2.8)':
     dependencies:
-      '@polkadot-api/signers-common': 0.3.0(rxjs@7.8.2)
+      '@polkadot-api/signers-common': 0.3.0(patch_hash=365a34617de2ae3ad2f7e009f7f3e20e0078448fbfc93c395d323f0e21b75d37)(rxjs@7.8.2)
       '@polkadot-api/tx-creator': 0.2.0(rxjs@7.8.2)
       '@react-rxjs/utils': 0.9.7(@react-rxjs/core@0.10.8(react@19.2.8)(rxjs@7.8.2))(react@19.2.8)(rxjs@7.8.2)
       '@rx-state/core': 0.1.4(rxjs@7.8.2)
@@ -5892,7 +5893,7 @@ snapshots:
   '@polkahub/vault@0.9.1(@types/react-dom@19.2.7(@types/react@19.2.18))(@types/react@19.2.18)(esbuild@0.28.1)(react-dom@19.2.8(react@19.2.8))(react@19.2.8)':
     dependencies:
       '@polkadot-api/merkleize-metadata': 1.3.1
-      '@polkadot-api/signers-common': 0.3.0(rxjs@7.8.2)
+      '@polkadot-api/signers-common': 0.3.0(patch_hash=365a34617de2ae3ad2f7e009f7f3e20e0078448fbfc93c395d323f0e21b75d37)(rxjs@7.8.2)
       '@polkadot-api/substrate-bindings': 0.21.0
       '@polkahub/context': 0.9.1(@types/react@19.2.18)(esbuild@0.28.1)(react-dom@19.2.8(react@19.2.8))(react@19.2.8)
       '@polkahub/plugin': 0.9.1(@react-rxjs/core@0.10.8(react@19.2.8)(rxjs@7.8.2))(esbuild@0.28.1)(react@19.2.8)
@@ -9234,7 +9235,7 @@ snapshots:
       '@polkadot-api/observable-client': 0.19.0(rxjs@7.8.2)
       '@polkadot-api/pjs-signer': 0.8.0(rxjs@7.8.2)
       '@polkadot-api/raw-tx-creator': 0.4.0(rxjs@7.8.2)
-      '@polkadot-api/signers-common': 0.3.0(rxjs@7.8.2)
+      '@polkadot-api/signers-common': 0.3.0(patch_hash=365a34617de2ae3ad2f7e009f7f3e20e0078448fbfc93c395d323f0e21b75d37)(rxjs@7.8.2)
       '@polkadot-api/sm-provider': 0.3.8(@polkadot-api/smoldot@0.4.7)
       '@polkadot-api/smoldot': 0.4.7
       '@polkadot-api/substrate-bindings': 0.21.0
@@ -9263,7 +9264,7 @@ snapshots:
       '@polkadot-api/observable-client': 0.19.1(rxjs@7.8.2)
       '@polkadot-api/pjs-signer': 0.8.1(rxjs@7.8.2)
       '@polkadot-api/raw-tx-creator': 0.4.1(rxjs@7.8.2)
-      '@polkadot-api/signers-common': 0.3.1(rxjs@7.8.2)
+      '@polkadot-api/signers-common': 0.3.1(patch_hash=365a34617de2ae3ad2f7e009f7f3e20e0078448fbfc93c395d323f0e21b75d37)(rxjs@7.8.2)
       '@polkadot-api/sm-provider': 0.3.8(@polkadot-api/smoldot@0.4.7)
       '@polkadot-api/smoldot': 0.4.7
       '@polkadot-api/substrate-bindings': 0.21.1
diff --git a/pnpm-workspace.yaml b/pnpm-workspace.yaml
index 00dbec0..62c54c2 100644
--- a/pnpm-workspace.yaml
+++ b/pnpm-workspace.yaml
@@ -9,4 +9,5 @@ minimumReleaseAgeExclude:
   - '@paraspell/sdk-core@14.3.0 || 14.3.4'
   - '@paraspell/sdk@14.3.0 || 14.3.4'
 patchedDependencies:
+  '@polkadot-api/signers-common': patches/@polkadot-api__signers-common.patch
   react18-json-view: patches/react18-json-view.patch
diff --git a/src/state/chains/networks/index.ts b/src/state/chains/networks/index.ts
index d543c39..830ae8c 100644
--- a/src/state/chains/networks/index.ts
+++ b/src/state/chains/networks/index.ts
@@ -1,6 +1,7 @@
 import ksmRawNetworks from "./kusama.json"
 import paseoRawNetworks from "./paseo.json"
 import polkadotRawNetworks from "./polkadot.json"
+import quantusRawNetworks from "./quantus.json"
 import westendRawNetworks from "./westend.json"
 
 export type Network = {
@@ -16,12 +17,13 @@ export type NetworkCategory = {
   networks: Network[]
 }
 
-const [Polkadot, Kusama, Paseo, Westend] = (
+const [Polkadot, Kusama, Paseo, Westend, Quantus] = (
   [
     polkadotRawNetworks,
     ksmRawNetworks,
     paseoRawNetworks,
     westendRawNetworks,
+    quantusRawNetworks,
   ] as const
 ).map((n): Network[] =>
   n.map((x) => ({
@@ -29,11 +31,20 @@ const [Polkadot, Kusama, Paseo, Westend] = (
     lightclient: !!x.hasChainSpecs,
     id: x.id,
     display: x.display,
-    relayChain: x.relayChainInfo?.id,
+    // Quantus is a solo chain and its entries carry no `relayChainInfo`, so the
+    // union of the imported JSON literals no longer has the property on every
+    // arm. Narrowed rather than cast: a typo in one of the relay-chain files
+    // should still be a type error.
+    relayChain: "relayChainInfo" in x ? x.relayChainInfo?.id : undefined,
   })),
 )
 
+// Quantus first, and the default below. This console exists to exercise a
+// post-quantum chain; the Substrate networks stay because a signature that works
+// on both is the only evidence that the patch in patches/ widened a check rather
+// than broke one.
 const networks = {
+  Quantus,
   Polkadot,
   Kusama,
   Paseo,
@@ -69,4 +80,5 @@ export const addCustomNetwork = (uri: string) => {
   getCustomNetwork().endpoints[uri] = uri
 }
 
-export const defaultNetwork = Polkadot[0]
+// Mainnet. The console opens on the chain it was forked for.
+export const defaultNetwork = Quantus[0]
diff --git a/src/state/chains/networks/quantus.json b/src/state/chains/networks/quantus.json
new file mode 100644
index 0000000..9284a4c
--- /dev/null
+++ b/src/state/chains/networks/quantus.json
@@ -0,0 +1,40 @@
+[
+  {
+    "id": "quantus",
+    "display": "Quantus",
+    "rpcs": {
+      "Quantus": "wss://rpc1-mainnet.quantus.com"
+    },
+    "nativeToken": {
+      "symbol": "QTC",
+      "decimals": 12
+    },
+    "hasChainSpecs": false
+  },
+  {
+    "id": "heisenberg",
+    "display": "Heisenberg",
+    "rpcs": {
+      "a1": "wss://a1-heisenberg.quantus.cat",
+      "a2": "wss://a2-heisenberg.quantus.cat"
+    },
+    "nativeToken": {
+      "symbol": "HEI",
+      "decimals": 12
+    },
+    "hasChainSpecs": false
+  },
+  {
+    "id": "planck",
+    "display": "Planck",
+    "rpcs": {
+      "a1": "wss://a1-planck.quantus.cat",
+      "a2": "wss://a2-planck.quantus.cat"
+    },
+    "nativeToken": {
+      "symbol": "PLK",
+      "decimals": 12
+    },
+    "hasChainSpecs": false
+  }
+]