diff --git a/internal/interpreter/testdata/numscript-cookbook/experimental/meta-calc.num b/internal/interpreter/testdata/numscript-cookbook/experimental/meta-calc.num
new file mode 100644
index 00000000..826833cc
--- /dev/null
+++ b/internal/interpreter/testdata/numscript-cookbook/experimental/meta-calc.num
@@ -0,0 +1,10 @@
+vars {
+  number $x = 10 + 1
+}
+
+send [USD/2 10] (
+  source = @world
+  destination = @alice
+)
+
+set_tx_meta("key", $x/2)
diff --git a/internal/interpreter/testdata/numscript-cookbook/experimental/meta-calc.num.specs.json b/internal/interpreter/testdata/numscript-cookbook/experimental/meta-calc.num.specs.json
new file mode 100644
index 00000000..8f5f92e2
--- /dev/null
+++ b/internal/interpreter/testdata/numscript-cookbook/experimental/meta-calc.num.specs.json
@@ -0,0 +1,16 @@
+{
+  "$schema": "https://raw.githubusercontent.com/formancehq/numscript/main/specs.schema.json",
+  "featureFlags": [
+    "experimental-overdraft-function",
+    "experimental-mid-script-function-call",
+    "experimental-oneof"
+  ],
+  "testCases": [
+    {
+      "it": "sets the expected meta",
+      "expect.txMetadata": {
+        "key": "11/2"
+      }
+    }
+  ]
+}
diff --git a/internal/interpreter/testdata/numscript-cookbook/experimental/mixed-source-prefer-single-source.num b/internal/interpreter/testdata/numscript-cookbook/experimental/mixed-source-prefer-single-source.num
new file mode 100644
index 00000000..d9821f5e
--- /dev/null
+++ b/internal/interpreter/testdata/numscript-cookbook/experimental/mixed-source-prefer-single-source.num
@@ -0,0 +1,15 @@
+vars {
+  number $amt
+}
+
+send [USD $amt] (
+  source = oneof {
+    @s1
+    @s2
+    {
+      @s1
+      @s2
+    }
+  }
+  destination = @dest
+)
diff --git a/internal/interpreter/testdata/numscript-cookbook/experimental/mixed-source-prefer-single-source.num.specs.json b/internal/interpreter/testdata/numscript-cookbook/experimental/mixed-source-prefer-single-source.num.specs.json
new file mode 100644
index 00000000..431cca04
--- /dev/null
+++ b/internal/interpreter/testdata/numscript-cookbook/experimental/mixed-source-prefer-single-source.num.specs.json
@@ -0,0 +1,81 @@
+{
+  "$schema": "https://raw.githubusercontent.com/formancehq/numscript/main/specs.schema.json",
+  "variables": {
+    "amt": "10"
+  },
+  "featureFlags": ["experimental-oneof"],
+  "testCases": [
+    {
+      "it": "sends from the first source when there is enough balance",
+      "balances": {
+        "s1": {
+          "USD": 999
+        }
+      },
+      "expect.postings": [
+        {
+          "source": "s1",
+          "destination": "dest",
+          "amount": 10,
+          "asset": "USD"
+        }
+      ]
+    },
+    {
+      "it": "sends from the second one when it has enough balance but the first one doesn't",
+      "balances": {
+        "s1": {
+          "USD": 9
+        },
+        "s2": {
+          "USD": 999
+        }
+      },
+      "expect.postings": [
+        {
+          "source": "s2",
+          "destination": "dest",
+          "amount": 10,
+          "asset": "USD"
+        }
+      ]
+    },
+    {
+      "it": "sends partially from both when none of them has enough balance on its own",
+      "balances": {
+        "s1": {
+          "USD": 6
+        },
+        "s2": {
+          "USD": 9
+        }
+      },
+      "expect.postings": [
+        {
+          "source": "s1",
+          "destination": "dest",
+          "amount": 6,
+          "asset": "USD"
+        },
+        {
+          "source": "s2",
+          "destination": "dest",
+          "amount": 4,
+          "asset": "USD"
+        }
+      ]
+    },
+    {
+      "it": "fails if there aren't enough funds between all sources",
+      "balances": {
+        "s1": {
+          "USD": 5
+        },
+        "s2": {
+          "USD": 4
+        }
+      },
+      "expect.missingFunds": true
+    }
+  ]
+}
diff --git a/internal/interpreter/testdata/numscript-cookbook/experimental/top-up-many.num b/internal/interpreter/testdata/numscript-cookbook/experimental/top-up-many.num
new file mode 100644
index 00000000..34c69cfc
--- /dev/null
+++ b/internal/interpreter/testdata/numscript-cookbook/experimental/top-up-many.num
@@ -0,0 +1,13 @@
+vars {
+  number $amt
+}
+
+
+send [EUR $amt] (
+  source = @world
+  destination = oneof {
+    max overdraft(@alice, EUR) to @alice
+    max overdraft(@bob, EUR) to @bob
+    remaining kept
+  }
+)
diff --git a/internal/interpreter/testdata/numscript-cookbook/experimental/top-up-many.num.specs.json b/internal/interpreter/testdata/numscript-cookbook/experimental/top-up-many.num.specs.json
new file mode 100644
index 00000000..2c1cbc95
--- /dev/null
+++ b/internal/interpreter/testdata/numscript-cookbook/experimental/top-up-many.num.specs.json
@@ -0,0 +1,56 @@
+{
+  "$schema": "https://raw.githubusercontent.com/formancehq/numscript/main/specs.schema.json",
+  "featureFlags": [
+    "experimental-overdraft-function",
+    "experimental-mid-script-function-call",
+    "experimental-oneof"
+  ],
+  "variables": {
+    "amt": "100"
+  },
+  "testCases": [
+    {
+      "it": "should be a noop when all balances are >= 0",
+      "balances": { "alice": { "EUR": 100 }, "bob": { "EUR": 200 } },
+      "expect.postings": []
+    },
+    {
+      "it": "should prioritize alice when both have missing funds",
+      "balances": {
+        "alice": { "EUR": -120 },
+        "bob": { "EUR": -120 }
+      },
+      "expect.postings": [
+        {
+          "source": "world",
+          "destination": "alice",
+          "amount": 100,
+          "asset": "EUR"
+        }
+      ]
+    },
+    {
+      "it": "doesn't send funds to alice if there aren't enough funds for the account to be topped-up",
+      "balances": {
+        "alice": { "EUR": -80 },
+        "bob": { "EUR": -120 }
+      },
+      "expect.postings": [
+        {
+          "source": "world",
+          "destination": "bob",
+          "amount": 100,
+          "asset": "EUR"
+        }
+      ]
+    },
+    {
+      "it": "funds are kept if there are spare funds",
+      "balances": {
+        "alice": { "EUR": -10 },
+        "bob": { "EUR": -20 }
+      },
+      "expect.postings": []
+    }
+  ]
+}
diff --git a/internal/interpreter/testdata/numscript-cookbook/experimental/top-up.num b/internal/interpreter/testdata/numscript-cookbook/experimental/top-up.num
new file mode 100644
index 00000000..322efb63
--- /dev/null
+++ b/internal/interpreter/testdata/numscript-cookbook/experimental/top-up.num
@@ -0,0 +1,8 @@
+vars {
+  monetary $alice_overdraft = overdraft(@alice, EUR)
+}
+
+send $alice_overdraft (
+  source = @world
+  destination = @alice
+)
diff --git a/internal/interpreter/testdata/numscript-cookbook/experimental/top-up.num.specs.json b/internal/interpreter/testdata/numscript-cookbook/experimental/top-up.num.specs.json
new file mode 100644
index 00000000..fbaddc23
--- /dev/null
+++ b/internal/interpreter/testdata/numscript-cookbook/experimental/top-up.num.specs.json
@@ -0,0 +1,32 @@
+{
+  "$schema": "https://raw.githubusercontent.com/formancehq/numscript/main/specs.schema.json",
+  "featureFlags": ["experimental-overdraft-function"],
+  "testCases": [
+    {
+      "it": "should not emit postings",
+      "balances": { "alice": { "EUR": 100 } },
+      "expect.postings": []
+    },
+    {
+      "it": "should send the missing amount to an overdraft account",
+      "balances": { "alice": { "EUR": -100 } },
+      "expect.volumes": {
+        "alice": { "EUR": 0 },
+        "world": { "EUR": -100 }
+      },
+      "expect.movements": {
+        "world": {
+          "alice": { "EUR": 100 }
+        }
+      },
+      "expect.postings": [
+        {
+          "source": "world",
+          "destination": "alice",
+          "amount": 100,
+          "asset": "EUR"
+        }
+      ]
+    }
+  ]
+}
diff --git a/internal/interpreter/testdata/numscript-cookbook/experimental/transfer-example.num b/internal/interpreter/testdata/numscript-cookbook/experimental/transfer-example.num
new file mode 100644
index 00000000..cf887c0a
--- /dev/null
+++ b/internal/interpreter/testdata/numscript-cookbook/experimental/transfer-example.num
@@ -0,0 +1,11 @@
+vars {
+  number $amt
+  account $dest
+  monetary $bank_overdraft = overdraft(@bank_account, EUR)
+}
+
+send [EUR $amt] (
+  source = max $bank_overdraft from @wallet
+  destination = $dest
+)
+
diff --git a/internal/interpreter/testdata/numscript-cookbook/experimental/transfer-example.num.specs.json b/internal/interpreter/testdata/numscript-cookbook/experimental/transfer-example.num.specs.json
new file mode 100644
index 00000000..fd4844de
--- /dev/null
+++ b/internal/interpreter/testdata/numscript-cookbook/experimental/transfer-example.num.specs.json
@@ -0,0 +1,45 @@
+{
+  "$schema": "https://raw.githubusercontent.com/formancehq/numscript/main/specs.schema.json",
+  "featureFlags": [
+    "experimental-overdraft-function",
+    "experimental-mid-script-function-call",
+    "experimental-oneof"
+  ],
+  "variables": {
+    "amt": "100",
+    "dest": "alice"
+  },
+  "testCases": [
+    {
+      "it": "should authorize transfer if both wallet and bank accounts display enough balance",
+      "balances": {
+        "wallet": { "EUR": 100 },
+        "bank_account": { "EUR": -100 }
+      },
+      "expect.postings": [
+        {
+          "source": "wallet",
+          "destination": "alice",
+          "amount": 100,
+          "asset": "EUR"
+        }
+      ]
+    },
+    {
+      "it": "should not authorize transfer if wallet does not display enough balance and bank account does",
+      "balances": {
+        "wallet": { "EUR": 50 },
+        "bank_account": { "EUR": -100 }
+      },
+      "expect.missingFunds": true
+    },
+    {
+      "it": "should not authorize transfer if bank account does not display enough balance and wallet does",
+      "balances": {
+        "wallet": { "EUR": 100 },
+        "bank_account": { "EUR": -50 }
+      },
+      "expect.missingFunds": true
+    }
+  ]
+}
diff --git a/internal/interpreter/testdata/numscript-cookbook/max-fee.num b/internal/interpreter/testdata/numscript-cookbook/max-fee.num
new file mode 100644
index 00000000..56235357
--- /dev/null
+++ b/internal/interpreter/testdata/numscript-cookbook/max-fee.num
@@ -0,0 +1,16 @@
+vars {
+  number $amt
+  number $cap
+  portion $fee
+}
+
+send [USD $amt] (
+  source = @world
+  destination = {
+    $fee to {
+      max [USD $cap] to @fees
+      remaining to @dest
+    }
+    remaining to @dest
+  }
+)
diff --git a/internal/interpreter/testdata/numscript-cookbook/max-fee.num.specs.json b/internal/interpreter/testdata/numscript-cookbook/max-fee.num.specs.json
new file mode 100644
index 00000000..804b3a15
--- /dev/null
+++ b/internal/interpreter/testdata/numscript-cookbook/max-fee.num.specs.json
@@ -0,0 +1,55 @@
+{
+  "$schema": "https://raw.githubusercontent.com/formancehq/numscript/main/specs.schema.json",
+  "variables": {
+    "cap": "10",
+    "fee": "10%"
+  },
+  "testCases": [
+    {
+      "it": "it sends 10% of the fee when lower than cap",
+      "variables": {
+        "amt": "10"
+      },
+      "expect.postings": [
+        {
+          "source": "world",
+          "destination": "fees",
+          "amount": 1,
+          "asset": "USD"
+        },
+        {
+          "source": "world",
+          "destination": "dest",
+          "amount": 9,
+          "asset": "USD"
+        }
+      ]
+    },
+    {
+      "it": "it caps the fee to the $cap",
+      "variables": {
+        "amt": "500"
+      },
+      "expect.postings": [
+        {
+          "source": "world",
+          "destination": "fees",
+          "amount": 10,
+          "asset": "USD"
+        },
+        {
+          "source": "world",
+          "destination": "dest",
+          "amount": 40,
+          "asset": "USD"
+        },
+        {
+          "source": "world",
+          "destination": "dest",
+          "amount": 450,
+          "asset": "USD"
+        }
+      ]
+    }
+  ]
+}
diff --git a/internal/interpreter/testdata/numscript-cookbook/mixed-source-dest-allotment.num b/internal/interpreter/testdata/numscript-cookbook/mixed-source-dest-allotment.num
new file mode 100644
index 00000000..a1a37613
--- /dev/null
+++ b/internal/interpreter/testdata/numscript-cookbook/mixed-source-dest-allotment.num
@@ -0,0 +1,11 @@
+send [USD 77] (
+  source = {
+    10% from @src1
+    20% from @src2
+    remaining from @world
+  }
+  destination = {
+    1/2 to @dest1
+    1/2 to @dest2
+  }
+)
diff --git a/internal/interpreter/testdata/numscript-cookbook/mixed-source-dest-allotment.num.specs.json b/internal/interpreter/testdata/numscript-cookbook/mixed-source-dest-allotment.num.specs.json
new file mode 100644
index 00000000..cd0bc9e9
--- /dev/null
+++ b/internal/interpreter/testdata/numscript-cookbook/mixed-source-dest-allotment.num.specs.json
@@ -0,0 +1,42 @@
+{
+  "$schema": "https://raw.githubusercontent.com/formancehq/numscript/main/specs.schema.json",
+  "testCases": [
+    {
+      "it": "matches sources and destinations allotments",
+      "balances": {
+        "src1": {
+          "USD": 999
+        },
+        "src2": {
+          "USD": 999
+        }
+      },
+      "expect.postings": [
+        {
+          "source": "src1",
+          "destination": "dest1",
+          "amount": 8,
+          "asset": "USD"
+        },
+        {
+          "source": "src2",
+          "destination": "dest1",
+          "amount": 16,
+          "asset": "USD"
+        },
+        {
+          "source": "world",
+          "destination": "dest1",
+          "amount": 15,
+          "asset": "USD"
+        },
+        {
+          "source": "world",
+          "destination": "dest2",
+          "amount": 38,
+          "asset": "USD"
+        }
+      ]
+    }
+  ]
+}
diff --git a/internal/interpreter/testdata/numscript-cookbook/send-max.num b/internal/interpreter/testdata/numscript-cookbook/send-max.num
new file mode 100644
index 00000000..51801a83
--- /dev/null
+++ b/internal/interpreter/testdata/numscript-cookbook/send-max.num
@@ -0,0 +1,4 @@
+send [USD *] (
+  source = max [USD 100] from @src
+  destination = @dest
+)
diff --git a/internal/interpreter/testdata/numscript-cookbook/send-max.num.specs.json b/internal/interpreter/testdata/numscript-cookbook/send-max.num.specs.json
new file mode 100644
index 00000000..d2e32539
--- /dev/null
+++ b/internal/interpreter/testdata/numscript-cookbook/send-max.num.specs.json
@@ -0,0 +1,33 @@
+{
+  "$schema": "https://raw.githubusercontent.com/formancehq/numscript/main/specs.schema.json",
+  "testCases": [
+    {
+      "it": "is capped to USD100 when balance is higher",
+      "balances": {
+        "src": { "USD": 999 }
+      },
+      "expect.postings": [
+        {
+          "source": "src",
+          "destination": "dest",
+          "amount": 100,
+          "asset": "USD"
+        }
+      ]
+    },
+    {
+      "it": "allows sending less than the cap when balance is not enough",
+      "balances": {
+        "src": { "USD": 42 }
+      },
+      "expect.postings": [
+        {
+          "source": "src",
+          "destination": "dest",
+          "amount": 42,
+          "asset": "USD"
+        }
+      ]
+    }
+  ]
+}
diff --git a/internal/interpreter/testdata/numscript-cookbook/top-up-max.num b/internal/interpreter/testdata/numscript-cookbook/top-up-max.num
new file mode 100644
index 00000000..8246036a
--- /dev/null
+++ b/internal/interpreter/testdata/numscript-cookbook/top-up-max.num
@@ -0,0 +1,14 @@
+vars {
+  monetary $jon_balance = balance(@jon, EUR/2)
+
+  // The amount to send
+  monetary $amt
+
+  // The end balance we don't want to exceed
+  monetary $limit
+}
+
+send $amt (
+  source = max $limit - $jon_balance from @alice
+  destination = @jon 
+)
diff --git a/internal/interpreter/testdata/numscript-cookbook/top-up-max.num.specs.json b/internal/interpreter/testdata/numscript-cookbook/top-up-max.num.specs.json
new file mode 100644
index 00000000..0ef59acf
--- /dev/null
+++ b/internal/interpreter/testdata/numscript-cookbook/top-up-max.num.specs.json
@@ -0,0 +1,55 @@
+{
+  "$schema": "https://raw.githubusercontent.com/formancehq/numscript/main/specs.schema.json",
+  "variables": {
+    "amt": "EUR/2 100",
+    "limit": "EUR/2 150"
+  },
+  "balances": {
+    "alice": {
+      "EUR/2": 9999
+    }
+  },
+  "testCases": [
+    {
+      "it": "should send the amount when destination doesn't reach 150",
+      "balances": {
+        "jon": {
+          "EUR/2": 0
+        }
+      },
+      "expect.postings": [
+        {
+          "source": "alice",
+          "destination": "jon",
+          "amount": 100,
+          "asset": "EUR/2"
+        }
+      ]
+    },
+    {
+      "it": "should send the amount when destination doesn't reach 150 (2)",
+      "balances": {
+        "jon": {
+          "EUR/2": 50
+        }
+      },
+      "expect.postings": [
+        {
+          "source": "alice",
+          "destination": "jon",
+          "amount": 100,
+          "asset": "EUR/2"
+        }
+      ]
+    },
+    {
+      "it": "should fail if the end balance would exceed 150",
+      "balances": {
+        "jon": {
+          "EUR/2": 51
+        }
+      },
+      "expect.missingFunds": true
+    }
+  ]
+}