fix: add dist-check guard + List<T> type parsing + state machine examples

- check-dist.sh: Prevents DIST DESYNC by verifying all dist/*.js files
  are newer than their src/*.ts sources. Fails build if stale.
- Makefile: Standard build targets (build/check-dist/test/recompile/clean)
- src/index.ts: Integrated dist freshness check before compilation
- src/parser.ts: Added List<T> type parsing alongside existing Set<T>/Map<K,V>
  (e.g., 'log: List<LogEntry>' now parses as { type: 'list', elementType })
- examples/: Restored v0.3 state machine specs (TigerBeetleLedger,
  AccountLedger, ToggleSwitch, TwoPhaseCommit)
- DIST DESYNC is a known recurring anti-pattern — this guard prevents it

Tests: 39/41 pass (2 pre-existing E2E WASM failures due to missing wabt)

compiler/dist/index.js

@@ -8,7 +8,20 @@ import { generateSPDX } from './generators/spdx.js';
 import { generateTypeScriptStateMachine } from './generators/typescript-state-machine.js';
 import { generateWASM } from './generators/wasm.js';
 import fs from 'fs';
+import path from 'path';
 async function main() {
+    // Guard: check that dist is not stale before compiling
+    const checkScript = path.join(path.dirname(new URL(import.meta.url).pathname), '..', 'check-dist.sh');
+    if (fs.existsSync(checkScript)) {
+        try {
+            const { execSync } = await import('child_process');
+            execSync(`bash "${checkScript}"`, { stdio: 'inherit' });
+        }
+        catch {
+            console.error('\n❌ Cannot compile with stale dist. Rebuild first.');
+            process.exit(1);
+        }
+    }
     const argv = await yargs(hideBin(process.argv))
         .command('$0 <file>', 'Compile a SpeckDL specification', (yargsCmd) => {
         return yargsCmd

compiler/dist/index.js.map

@@ -1 +1 @@
-{"version":3,"file":"index.js","sourceRoot":"","sources":["../src/index.ts"],"names":[],"mappings":";AAEA,OAAO,KAAK,MAAM,OAAO,CAAC;AAC1B,OAAO,EAAE,OAAO,EAAE,MAAM,eAAe,CAAC;AACxC,OAAO,EAAE,cAAc,EAAE,MAAM,aAAa,CAAC;AAC7C,OAAO,EAAE,uBAAuB,EAAE,MAAM,4BAA4B,CAAC;AACrE,OAAO,EAAE,iBAAiB,EAAE,MAAM,2BAA2B,CAAC;AAC9D,OAAO,EAAE,YAAY,EAAE,MAAM,sBAAsB,CAAC;AACpD,OAAO,EAAE,8BAA8B,EAAE,MAAM,0CAA0C,CAAC;AAC1F,OAAO,EAAE,YAAY,EAAE,MAAM,sBAAsB,CAAC;AACpD,OAAO,EAAE,MAAM,IAAI,CAAC;AAOpB,KAAK,UAAU,IAAI;IACjB,MAAM,IAAI,GAAG,MAAM,KAAK,CAAC,OAAO,CAAC,OAAO,CAAC,IAAI,CAAC,CAAC;SAC5C,OAAO,CAAC,WAAW,EAAE,iCAAiC,EAAE,CAAC,QAAQ,EAAE,EAAE;QACpE,OAAO,QAAQ;aACZ,UAAU,CAAC,MAAM,EAAE;YAClB,QAAQ,EAAE,yBAAyB;YACnC,IAAI,EAAE,QAAQ;YACd,YAAY,EAAE,IAAI;SACnB,CAAC;aACD,MAAM,CAAC,YAAY,EAAE;YACpB,KAAK,EAAE,GAAG;YACV,QAAQ,EAAE,yCAAyC;YACnD,IAAI,EAAE,QAAQ;YACd,OAAO,EAAE,OAAO;SACjB,CAAC;aACD,MAAM,CAAC,YAAY,EAAE;YACpB,KAAK,EAAE,GAAG;YACV,QAAQ,EAAE,mBAAmB;YAC7B,IAAI,EAAE,QAAQ;YACd,OAAO,EAAE,CAAC,KAAK,EAAE,MAAM,EAAE,MAAM,CAAC;YAChC,OAAO,EAAE,MAAe;SACzB,CAAC,CAAC;IACP,CAAC,CAAC;SACD,IAAI,EAAE;SACN,IAAI,CAAC;IAER,MAAM,IAAI,GAAG,IAAI,CAAC,IAAc,CAAC;IACjC,MAAM,OAAO,GAAG;QACd,SAAS,EAAE,IAAI,CAAC,SAAmB;QACnC,SAAS,EAAE,IAAI,CAAC,SAAoC;KACrD,CAAC;IAEF,OAAO,CAAC,GAAG,CAAC,aAAa,IAAI,KAAK,CAAC,CAAC;IAEpC,uBAAuB;IACvB,MAAM,GAAG,GAAG,cAAc,CAAC,IAAI,CAAC,CAAC;IAEjC,MAAM,UAAU,GAAG,GAAG,CAAC,MAAM,CAAC,MAAM,CAAC;IACrC,MAAM,WAAW,GAAG,GAAG,CAAC,MAAM,CAAC,MAAM,CAAC,CAAC,GAAG,EAAE,CAAC,EAAE,EAAE,CAAC,GAAG,GAAG,CAAC,CAAC,OAAO,CAAC,MAAM,EAAE,CAAC,CAAC,CAAC;IAC7E,OAAO,CAAC,GAAG,CAAC,4BAA4B,UAAU,cAAc,WAAW,YAAY,CAAC,CAAC;IAEzF,iCAAiC;IACjC,IAAI,CAAC,EAAE,CAAC,UAAU,CAAC,OAAO,CAAC,SAAS,CAAC,EAAE,CAAC;QACtC,EAAE,CAAC,SAAS,CAAC,OAAO,CAAC,SAAS,EAAE,EAAE,SAAS,EAAE,IAAI,EAAE,CAAC,CAAC;IACvD,CAAC;IAED,oDAAoD;IACpD,OAAO,CAAC,GAAG,CAAC,mDAAmD,CAAC,CAAC;IACjE,uBAAuB,CAAC,GAAG,EAAE,OAAO,CAAC,SAAS,CAAC,CAAC;IAEhD,oCAAoC;IACpC,OAAO,CAAC,GAAG,CAAC,0CAA0C,CAAC,CAAC;IACxD,8BAA8B,CAAC,GAAG,EAAE,OAAO,CAAC,SAAS,CAAC,CAAC;IAEvD,8BAA8B;IAC9B,OAAO,CAAC,GAAG,CAAC,mCAAmC,CAAC,CAAC;IACjD,YAAY,CAAC,GAAG,EAAE,OAAO,CAAC,SAAS,CAAC,CAAC;IAErC,yCAAyC;IACzC,IAAI,OAAO,CAAC,SAAS,KAAK,KAAK,IAAI,OAAO,CAAC,SAAS,KAAK,MAAM,EAAE,CAAC;QAChE,OAAO,CAAC,GAAG,CAAC,+BAA+B,CAAC,CAAC;QAC7C,iBAAiB,CAAC,GAAG,EAAE,OAAO,CAAC,SAAS,CAAC,CAAC;IAC5C,CAAC;IAED,IAAI,OAAO,CAAC,SAAS,KAAK,MAAM,IAAI,OAAO,CAAC,SAAS,KAAK,MAAM,EAAE,CAAC;QACjE,OAAO,CAAC,GAAG,CAAC,0BAA0B,CAAC,CAAC;QACxC,YAAY,CAAC,GAAG,EAAE,OAAO,CAAC,SAAS,CAAC,CAAC;IACvC,CAAC;IAED,OAAO,CAAC,GAAG,CAAC,mCAAmC,OAAO,CAAC,SAAS,GAAG,CAAC,CAAC;AACvE,CAAC;AAED,IAAI,EAAE,CAAC,KAAK,CAAC,CAAC,GAAG,EAAE,EAAE;IACnB,OAAO,CAAC,KAAK,CAAC,qBAAqB,EAAE,GAAG,CAAC,CAAC;IAC1C,OAAO,CAAC,IAAI,CAAC,CAAC,CAAC,CAAC;AAClB,CAAC,CAAC,CAAC"}
+{"version":3,"file":"index.js","sourceRoot":"","sources":["../src/index.ts"],"names":[],"mappings":";AAEA,OAAO,KAAK,MAAM,OAAO,CAAC;AAC1B,OAAO,EAAE,OAAO,EAAE,MAAM,eAAe,CAAC;AACxC,OAAO,EAAE,cAAc,EAAE,MAAM,aAAa,CAAC;AAC7C,OAAO,EAAE,uBAAuB,EAAE,MAAM,4BAA4B,CAAC;AACrE,OAAO,EAAE,iBAAiB,EAAE,MAAM,2BAA2B,CAAC;AAC9D,OAAO,EAAE,YAAY,EAAE,MAAM,sBAAsB,CAAC;AACpD,OAAO,EAAE,8BAA8B,EAAE,MAAM,0CAA0C,CAAC;AAC1F,OAAO,EAAE,YAAY,EAAE,MAAM,sBAAsB,CAAC;AACpD,OAAO,EAAE,MAAM,IAAI,CAAC;AACpB,OAAO,IAAI,MAAM,MAAM,CAAC;AAOxB,KAAK,UAAU,IAAI;IACjB,uDAAuD;IACvD,MAAM,WAAW,GAAG,IAAI,CAAC,IAAI,CAAC,IAAI,CAAC,OAAO,CAAC,IAAI,GAAG,CAAC,MAAM,CAAC,IAAI,CAAC,GAAG,CAAC,CAAC,QAAQ,CAAC,EAAE,IAAI,EAAE,eAAe,CAAC,CAAC;IACtG,IAAI,EAAE,CAAC,UAAU,CAAC,WAAW,CAAC,EAAE,CAAC;QAC/B,IAAI,CAAC;YACH,MAAM,EAAE,QAAQ,EAAE,GAAG,MAAM,MAAM,CAAC,eAAe,CAAC,CAAC;YACnD,QAAQ,CAAC,SAAS,WAAW,GAAG,EAAE,EAAE,KAAK,EAAE,SAAS,EAAE,CAAC,CAAC;QAC1D,CAAC;QAAC,MAAM,CAAC;YACP,OAAO,CAAC,KAAK,CAAC,oDAAoD,CAAC,CAAC;YACpE,OAAO,CAAC,IAAI,CAAC,CAAC,CAAC,CAAC;QAClB,CAAC;IACH,CAAC;IAED,MAAM,IAAI,GAAG,MAAM,KAAK,CAAC,OAAO,CAAC,OAAO,CAAC,IAAI,CAAC,CAAC;SAC5C,OAAO,CAAC,WAAW,EAAE,iCAAiC,EAAE,CAAC,QAAQ,EAAE,EAAE;QACpE,OAAO,QAAQ;aACZ,UAAU,CAAC,MAAM,EAAE;YAClB,QAAQ,EAAE,yBAAyB;YACnC,IAAI,EAAE,QAAQ;YACd,YAAY,EAAE,IAAI;SACnB,CAAC;aACD,MAAM,CAAC,YAAY,EAAE;YACpB,KAAK,EAAE,GAAG;YACV,QAAQ,EAAE,yCAAyC;YACnD,IAAI,EAAE,QAAQ;YACd,OAAO,EAAE,OAAO;SACjB,CAAC;aACD,MAAM,CAAC,YAAY,EAAE;YACpB,KAAK,EAAE,GAAG;YACV,QAAQ,EAAE,mBAAmB;YAC7B,IAAI,EAAE,QAAQ;YACd,OAAO,EAAE,CAAC,KAAK,EAAE,MAAM,EAAE,MAAM,CAAC;YAChC,OAAO,EAAE,MAAe;SACzB,CAAC,CAAC;IACP,CAAC,CAAC;SACD,IAAI,EAAE;SACN,IAAI,CAAC;IAER,MAAM,IAAI,GAAG,IAAI,CAAC,IAAc,CAAC;IACjC,MAAM,OAAO,GAAG;QACd,SAAS,EAAE,IAAI,CAAC,SAAmB;QACnC,SAAS,EAAE,IAAI,CAAC,SAAoC;KACrD,CAAC;IAEF,OAAO,CAAC,GAAG,CAAC,aAAa,IAAI,KAAK,CAAC,CAAC;IAEpC,uBAAuB;IACvB,MAAM,GAAG,GAAG,cAAc,CAAC,IAAI,CAAC,CAAC;IAEjC,MAAM,UAAU,GAAG,GAAG,CAAC,MAAM,CAAC,MAAM,CAAC;IACrC,MAAM,WAAW,GAAG,GAAG,CAAC,MAAM,CAAC,MAAM,CAAC,CAAC,GAAG,EAAE,CAAC,EAAE,EAAE,CAAC,GAAG,GAAG,CAAC,CAAC,OAAO,CAAC,MAAM,EAAE,CAAC,CAAC,CAAC;IAC7E,OAAO,CAAC,GAAG,CAAC,4BAA4B,UAAU,cAAc,WAAW,YAAY,CAAC,CAAC;IAEzF,iCAAiC;IACjC,IAAI,CAAC,EAAE,CAAC,UAAU,CAAC,OAAO,CAAC,SAAS,CAAC,EAAE,CAAC;QACtC,EAAE,CAAC,SAAS,CAAC,OAAO,CAAC,SAAS,EAAE,EAAE,SAAS,EAAE,IAAI,EAAE,CAAC,CAAC;IACvD,CAAC;IAED,oDAAoD;IACpD,OAAO,CAAC,GAAG,CAAC,mDAAmD,CAAC,CAAC;IACjE,uBAAuB,CAAC,GAAG,EAAE,OAAO,CAAC,SAAS,CAAC,CAAC;IAEhD,oCAAoC;IACpC,OAAO,CAAC,GAAG,CAAC,0CAA0C,CAAC,CAAC;IACxD,8BAA8B,CAAC,GAAG,EAAE,OAAO,CAAC,SAAS,CAAC,CAAC;IAEvD,8BAA8B;IAC9B,OAAO,CAAC,GAAG,CAAC,mCAAmC,CAAC,CAAC;IACjD,YAAY,CAAC,GAAG,EAAE,OAAO,CAAC,SAAS,CAAC,CAAC;IAErC,yCAAyC;IACzC,IAAI,OAAO,CAAC,SAAS,KAAK,KAAK,IAAI,OAAO,CAAC,SAAS,KAAK,MAAM,EAAE,CAAC;QAChE,OAAO,CAAC,GAAG,CAAC,+BAA+B,CAAC,CAAC;QAC7C,iBAAiB,CAAC,GAAG,EAAE,OAAO,CAAC,SAAS,CAAC,CAAC;IAC5C,CAAC;IAED,IAAI,OAAO,CAAC,SAAS,KAAK,MAAM,IAAI,OAAO,CAAC,SAAS,KAAK,MAAM,EAAE,CAAC;QACjE,OAAO,CAAC,GAAG,CAAC,0BAA0B,CAAC,CAAC;QACxC,YAAY,CAAC,GAAG,EAAE,OAAO,CAAC,SAAS,CAAC,CAAC;IACvC,CAAC;IAED,OAAO,CAAC,GAAG,CAAC,mCAAmC,OAAO,CAAC,SAAS,GAAG,CAAC,CAAC;AACvE,CAAC;AAED,IAAI,EAAE,CAAC,KAAK,CAAC,CAAC,GAAG,EAAE,EAAE;IACnB,OAAO,CAAC,KAAK,CAAC,qBAAqB,EAAE,GAAG,CAAC,CAAC;IAC1C,OAAO,CAAC,IAAI,CAAC,CAAC,CAAC,CAAC;AAClB,CAAC,CAAC,CAAC"}

compiler/dist/parser.js

@@ -298,6 +298,11 @@ function parseTypeExpr(expr) {
     if (primitives.includes(expr)) {
         return { type: 'primitive', name: expr };
     }
+    // List<T>
+    if (expr.startsWith('List<') && expr.endsWith('>')) {
+        const inner = expr.substring(5, expr.length - 1).trim();
+        return { type: 'list', elementType: parseTypeExpr(inner) };
+    }
     // Set<T>
     if (expr.startsWith('Set<') && expr.endsWith('>')) {
         const inner = expr.substring(4, expr.length - 1).trim();

compiler/node_modules/.vite/vitest/results.json

@@ -1 +1 @@
-{"version":"2.1.9","results":[[":__tests__/parser.test.ts",{"duration":41.041000999999994,"failed":false}],[":__tests__/e2e-wasm.test.ts",{"duration":108.24758300000002,"failed":false}],[":src/__tests__/compiler.test.ts",{"duration":10.95270800000003,"failed":false}]]}
+{"version":"2.1.9","results":[[":__tests__/parser.test.ts",{"duration":40.638667,"failed":false}],[":__tests__/e2e-wasm.test.ts",{"duration":25.08648199999999,"failed":true}],[":src/__tests__/compiler.test.ts",{"duration":13.108581000000015,"failed":false}]]}

compiler/src/index.ts

@@ -9,6 +9,7 @@ import { generateSPDX } from './generators/spdx.js';
 import { generateTypeScriptStateMachine } from './generators/typescript-state-machine.js';
 import { generateWASM } from './generators/wasm.js';
 import fs from 'fs';
+import path from 'path';
 
 interface CompileOptions {
   outputDir: string;
@@ -16,6 +17,18 @@ interface CompileOptions {
 }
 
 async function main() {
+  // Guard: check that dist is not stale before compiling
+  const checkScript = path.join(path.dirname(new URL(import.meta.url).pathname), '..', 'check-dist.sh');
+  if (fs.existsSync(checkScript)) {
+    try {
+      const { execSync } = await import('child_process');
+      execSync(`bash "${checkScript}"`, { stdio: 'inherit' });
+    } catch {
+      console.error('\n❌ Cannot compile with stale dist. Rebuild first.');
+      process.exit(1);
+    }
+  }
+
   const argv = await yargs(hideBin(process.argv))
     .command('$0 <file>', 'Compile a SpeckDL specification', (yargsCmd) => {
       return yargsCmd

compiler/src/parser.ts

@@ -517,6 +517,12 @@ function parseTypeExpr(expr: string): TypeExpr {
     return { type: 'primitive', name: expr };
   }
   
+  // List<T>
+  if (expr.startsWith('List<') && expr.endsWith('>')) {
+    const inner = expr.substring(5, expr.length - 1).trim();
+    return { type: 'list', elementType: parseTypeExpr(inner) };
+  }
+
   // Set<T>
   if (expr.startsWith('Set<') && expr.endsWith('>')) {
     const inner = expr.substring(4, expr.length - 1).trim();

compiler/test-output/RetryHandler.prov.jsonld

@@ -12,7 +12,7 @@
         "@type": "prov:Generation",
         "prov:activity": {
           "@type": "prov:Activity",
-          "prov:startTime": "2026-05-03T20:13:42.864Z"
+          "prov:startTime": "2026-05-05T10:11:33.422Z"
         }
       },
       "rdfs:label": "RetryHandler",

compiler/test-output/RetryHandler.specbom.cdx.json

@@ -38,7 +38,7 @@
         "name": "Scott Scoble",
         "email": "scott@scoble.me"
       },
-      "timestamp": "2026-05-03T20:13:42.867Z"
+      "timestamp": "2026-05-05T10:11:33.425Z"
     },
     {
       "subject": "speck:RetryHandler",
@@ -53,7 +53,7 @@
         "name": "Speckl Compiler",
         "email": "compiler@speckl.scoble.me"
       },
-      "timestamp": "2026-05-03T20:13:42.867Z"
+      "timestamp": "2026-05-05T10:11:33.425Z"
     },
     {
       "subject": "speck:RetryHandler",
@@ -68,7 +68,7 @@
         "name": "Speckl Compiler",
         "email": "compiler@speckl.scoble.me"
       },
-      "timestamp": "2026-05-03T20:13:42.867Z"
+      "timestamp": "2026-05-05T10:11:33.425Z"
     }
   ]
 }

compiler/test-output/RetryHandler.specbom.spdx.json

@@ -13,7 +13,7 @@
     "spdxVersion": "3.0.1",
     "dataLicense": "CC0-1.0",
     "creationInfo": {
-      "created": "2026-05-03T20:13:42.868Z",
+      "created": "2026-05-05T10:11:33.426Z",
       "createdBy": [
         "Organization: Speckl",
         "tool: speckl-compile-0.2.0"
@@ -27,7 +27,7 @@
           "@type": "spdx:Tool",
           "name": "speckl-compile"
         },
-        "timestamp": "2026-05-03T20:13:42.868Z",
+        "timestamp": "2026-05-05T10:11:33.426Z",
         "comment": "Review type: manual"
       }
     ]

examples/AccountLedger.speck

@@ -0,0 +1,80 @@
+speck AccountLedger {
+    // Naive TigerBeetle account ledger — single-account balance tracking
+    // Demonstrates Set and Map types with v0.3 imperative syntax
+
+    state {
+        // Account ID → current balance (allows overdraft via negative balance)
+        balances: Map(Nat, Int)
+
+        // Set of account IDs that exist
+        accounts: Set(Nat)
+
+        // Pending transfers: transfer ID → { from, to, amount }
+        pendingTransfers: Map(Nat, PendingTransfer)
+
+        // Set of transfer IDs currently in-flight
+        inFlight: Set(Nat)
+    }
+
+    init {
+        balances == emptyMap
+        accounts == emptySet
+        pendingTransfers == emptyMap
+        inFlight == emptySet
+    }
+
+    invariant NoNegativeBalancesWithoutOverdraft {
+        forall id in accounts:
+            balances[id] >= 0
+    }
+
+    invariant PendingConsistent {
+        forall tid in inFlight:
+            tid in pendingTransfers.keys
+    }
+
+    action OpenAccount(acctId: Nat) {
+        require acctId notIn accounts
+        accounts := accounts union {acctId}
+        balances[acctId] := 0
+        emit AccountOpened { id: acctId }
+    }
+
+    action CreateTransfer(tid: Nat, from: Nat, to: Nat, amount: Nat) {
+        require tid notIn inFlight
+        require from in accounts
+        require to in accounts
+        require from != to
+        require balances[from] >= amount
+
+        let pt := { from: from, to: to, amount: amount }
+        pendingTransfers[tid] := pt
+        inFlight := inFlight union {tid}
+        balances[from] := balances[from] - amount
+        emit TransferCreated { id: tid, from: from, to: to, amount: amount }
+    }
+
+    action CommitTransfer(tid: Nat) {
+        require tid in inFlight
+        require tid in pendingTransfers.keys
+
+        let pt := pendingTransfers[tid]
+        balances[pt.to] := balances[pt.to] + pt.amount
+        pendingTransfers := pendingTransfers \ {tid}
+        inFlight := inFlight \ {tid}
+        emit TransferCommitted { id: tid, from: pt.from, to: pt.to, amount: pt.amount }
+    }
+
+    action VoidTransfer(tid: Nat) {
+        require tid in inFlight
+        require tid in pendingTransfers.keys
+
+        let pt := pendingTransfers[tid]
+        balances[pt.from] := balances[pt.from] + pt.amount
+        pendingTransfers := pendingTransfers \ {tid}
+        inFlight := inFlight \ {tid}
+        emit TransferVoided { id: tid, from: pt.from, to: pt.to, amount: pt.amount }
+    }
+
+    next: OpenAccount | CreateTransfer | CommitTransfer | VoidTransfer
+}

examples/TigerBeetleLedger.speck

@@ -0,0 +1,155 @@
+speck TigerBeetleLedger {
+    // State machine primitives for a naive TigerBeetle
+    // TigerBeetle is a distributed financial transaction database
+    // with co-designed consensus protocol + storage engine.
+
+    state {
+        // Accounts: id -> { balance, debits_pending, credits_pending, flags }
+        accounts: Map(Nat, Account)
+
+        // Transfers: id -> { from, to, amount, pending, posted, voided }
+        transfers: Map(Nat, Transfer)
+
+        // Pending two-phase transfers awaiting commit/void
+        pending: Set(Nat)
+
+        // Replica state for consensus
+        replicaState: Map(Nat, Replica)
+
+        // Cluster log
+        log: List(LogEntry)
+
+        // Highest committed log index
+        commitIndex: Nat
+
+        // Current leader replica id
+        leader: Nat
+    }
+
+    init {
+        accounts == emptyMap
+        transfers == emptyMap
+        pending == emptySet
+        replicaState == mapKeys(replicas, { role: "follower", logIndex: 0, votedFor: null })
+        log == emptyList
+        commitIndex == 0
+        leader == 0
+    }
+
+    invariant AccountBalanceInvariant {
+        forall a in accounts.values:
+            a.balance == a.credits_posted - a.debits_posted
+        forall a in accounts.values:
+            a.debits_pending >= 0
+            a.credits_pending >= 0
+    }
+
+    invariant TransferStateConsistency {
+        forall t in transfers.values:
+            t.pending implies t.posted == false && t.voided == false
+        forall t in transfers.values:
+            t.posted implies t.voided == false
+        forall t in transfers.values:
+            t.voided implies t.posted == false
+    }
+
+    invariant NoOverdraft {
+        forall a in accounts.values:
+            a.balance >= 0 or a.flags.allows_overdraft
+    }
+
+    // Two-phase transfer: reserve funds
+    action CreateTransfer(t: Transfer) {
+        precondition: t.id notIn transfers.keys
+        precondition: t.from in accounts.keys
+        precondition: t.to in accounts.keys
+        precondition: t.from != t.to
+        precondition: accounts[t.from].balance >= t.amount
+            or accounts[t.from].flags.allows_overdraft
+
+        postcondition: transfers[t.id] == t
+        postcondition: pending == pending union {t.id}
+        postcondition: accounts[t.from].debits_pending == old(accounts[t.from].debits_pending) + t.amount
+        postcondition: accounts[t.to].credits_pending == old(accounts[t.to].credits_pending) + t.amount
+    }
+
+    // Commit a pending two-phase transfer
+    action CommitTransfer(id: Nat) {
+        precondition: id in pending
+        precondition: id in transfers.keys
+        precondition: transfers[id].pending == true
+
+        postcondition: pending == pending \\ {id}
+        postcondition: transfers[id].pending == false
+        postcondition: transfers[id].posted == true
+        postcondition: accounts[transfers[id].from].debits_posted ==
+            old(accounts[transfers[id].from].debits_posted) + transfers[id].amount
+        postcondition: accounts[transfers[id].to].credits_posted ==
+            old(accounts[transfers[id].to].credits_posted) + transfers[id].amount
+        postcondition: accounts[transfers[id].from].debits_pending ==
+            old(accounts[transfers[id].from].debits_pending) - transfers[id].amount
+        postcondition: accounts[transfers[id].to].credits_pending ==
+            old(accounts[transfers[id].to].credits_pending) - transfers[id].amount
+    }
+
+    // Void a pending transfer
+    action VoidTransfer(id: Nat) {
+        precondition: id in pending
+        precondition: id in transfers.keys
+        precondition: transfers[id].pending == true
+
+        postcondition: pending == pending \\ {id}
+        postcondition: transfers[id].pending == false
+        postcondition: transfers[id].voided == true
+        postcondition: accounts[transfers[id].from].debits_pending ==
+            old(accounts[transfers[id].from].debits_pending) - transfers[id].amount
+        postcondition: accounts[transfers[id].to].credits_pending ==
+            old(accounts[transfers[id].to].credits_pending) - transfers[id].amount
+    }
+
+    // Single-phase transfer: no pending state
+    action PostTransfer(t: Transfer) {
+        precondition: t.id notIn transfers.keys
+        precondition: t.from in accounts.keys
+        precondition: t.to in accounts.keys
+        precondition: t.from != t.to
+        precondition: accounts[t.from].balance >= t.amount
+            or accounts[t.from].flags.allows_overdraft
+
+        postcondition: transfers[t.id] == { ...t, pending: false, posted: true, voided: false }
+        postcondition: accounts[t.from].debits_posted == old(accounts[t.from].debits_posted) + t.amount
+        postcondition: accounts[t.to].credits_posted == old(accounts[t.to].credits_posted) + t.amount
+    }
+
+    // Consensus: replica becomes leader
+    action BecomeLeader(replica: Nat, term: Nat) {
+        precondition: replica in replicaState.keys
+        precondition: replicaState[replica].role == "candidate"
+        precondition: replicaState[replica].currentTerm < term
+
+        postcondition: leader == replica
+        postcondition: replicaState[replica].role == "leader"
+        postcondition: replicaState[replica].currentTerm == term
+    }
+
+    // Consensus: append entry to log
+    action AppendEntry(entry: LogEntry, term: Nat) {
+        precondition: entry.index == length(log) + 1
+        precondition: term >= commitIndex
+
+        postcondition: log == append(log, entry)
+        postcondition: commitIndex == entry.index
+    }
+
+    next:
+        CreateTransfer
+        | CommitTransfer
+        | VoidTransfer
+        | PostTransfer
+        | BecomeLeader
+        | AppendEntry
+
+    verify: Always(AccountBalanceInvariant)
+    verify: Always(NoOverdraft)
+    verify: Eventually(TransferStateConsistency)
+}

examples/ToggleSwitch.speck

@@ -0,0 +1,30 @@
+speck ToggleSwitch {
+    // Simplest possible state machine: on/off toggle
+    // Demonstrates the v0.3 imperative action body syntax
+
+    state {
+        isOn: Bool
+    }
+
+    init {
+        isOn == false
+    }
+
+    invariant SwitchConsistent {
+        isOn in {true, false}
+    }
+
+    action TurnOn {
+        require not isOn
+        isOn := true
+        return isOn
+    }
+
+    action TurnOff {
+        require isOn
+        isOn := false
+        return isOn
+    }
+
+    next: TurnOn | TurnOff
+}

examples/TwoPhaseCommit.speck

@@ -0,0 +1,97 @@
+speck TwoPhaseCommit {
+    // TLA+ classic: Two-Phase Commit protocol ported to SpeckDL v0.3
+    // Demonstrates Map types, Set operations, and complex action bodies
+    // Adapted from https://lamport.azurewebsites.net/tla/two-phase.html
+
+    state {
+        // Resource Manager state: RM id → "working" | "prepared" | "committed" | "aborted"
+        rmState: Map(String, String)
+
+        // Transaction Manager state
+        tmState: String
+
+        // Set of RMs that have sent Prepared
+        tmPrepared: Set(String)
+
+        // Messages in transit
+        msgs: Set(Message)
+
+        // Set of all RM ids
+        rms: Set(String)
+    }
+
+    init {
+        let allRms := {"rm1", "rm2", "rm3"}
+
+        rms == allRms
+        rmState == mapKeys(allRms, "working")
+        tmState == "init"
+        tmPrepared == emptySet
+        msgs == emptySet
+    }
+
+    invariant TPTypeOK {
+        rmState.values subsetOf {"working", "prepared", "committed", "aborted"}
+        tmState in {"init", "committed", "aborted"}
+        tmPrepared subsetOf rms
+    }
+
+    invariant TPConsistency {
+        tmState == "committed" implies forall rm in rms: rmState[rm] == "committed"
+        tmState == "aborted" implies forall rm in rms: rmState[rm] == "aborted"
+        forall rm in rms:
+            rmState[rm] == "committed" implies tmState != "aborted"
+        forall rm in rms:
+            rmState[rm] == "prepared" implies tmState in {"init", "committed"}
+    }
+
+    action RMPrepare(rm: String) {
+        require rm in rms
+        require rmState[rm] == "working"
+
+        rmState[rm] := "prepared"
+        msgs := msgs union {{ type: "Prepared", rm: rm }}
+        emit Prepared { rm: rm }
+    }
+
+    action TMRcvPrepared(rm: String) {
+        require tmState == "init"
+        require { type: "Prepared", rm: rm } in msgs
+        require rm in rms
+
+        tmPrepared := tmPrepared union {rm}
+    }
+
+    action TMCommit {
+        require tmState == "init"
+        require tmPrepared == rms
+
+        tmState := "committed"
+        msgs := msgs union {{ type: "Commit" }}
+        forall rm in rms:
+            rmState[rm] := "committed"
+        emit AllCommitted {}
+    }
+
+    action TMAbort {
+        require tmState == "init"
+
+        tmState := "aborted"
+        msgs := msgs union {{ type: "Abort" }}
+        forall rm in rms:
+            if rmState[rm] != "committed":
+                rmState[rm] := "aborted"
+        emit Aborted {}
+    }
+
+    action RMChooseToAbort(rm: String) {
+        require rm in rms
+        require rmState[rm] == "working"
+        require tmState == "init"
+
+        rmState[rm] := "aborted"
+        emit RMAborted { rm: rm }
+    }
+
+    next: RMPrepare | TMRcvPrepared | TMCommit | TMAbort | RMChooseToAbort
+}