diff --git a/examples/workflows/prompts/architect_freestyle.md b/examples/workflows/prompts/architect_freestyle.md
index 60bb2ec3..66e88db6 100644
--- a/examples/workflows/prompts/architect_freestyle.md
+++ b/examples/workflows/prompts/architect_freestyle.md
@@ -67,14 +67,17 @@ Emit a JSON object that validates against the `execution_plan` schema:
 - `from` and `to` must each be a declared stage `id` or the literal string `"done"`.
 - The normal forward edge uses `"type": "artifact_validated"` with `artifact_id` set to
   the `produces` id of the `from` stage.
+- Chain sequential stages: stage N's edge goes `to` stage N+1, not to `"done"`. Only the
+  final stage's edge points to `"done"`. A plan where an intermediate stage jumps to
+  `"done"` ends the whole workflow there and never runs the remaining stages.
 - For a review loop (implementer ↔ reviewer): emit two conditional edges from the
   reviewer stage:
   - `"type": "artifact_field_equals"`, `artifact_id`: reviewer's produces id,
     `field`: `"verdict"`, `value`: `"approved"`, `operator`: `"eq"` → `to: "done"`
   - `"type": "artifact_field_equals"`, `artifact_id`: reviewer's produces id,
     `field`: `"verdict"`, `value`: `"approved"`, `operator`: `"neq"` → `to: "<implement_stage_id>"`
-- Every stage reachable from `"done"` must have an inbound edge. Every non-terminal stage
-  must have an outbound edge.
+- Every stage except the first must have an inbound edge from an earlier stage; every
+  stage must have an outbound edge. Unreachable stages fail to compile.
 
 ## Constraints
 
diff --git a/infrastructure/workflow/src/main/kotlin/com/correx/infrastructure/workflow/ExecutionPlanCompiler.kt b/infrastructure/workflow/src/main/kotlin/com/correx/infrastructure/workflow/ExecutionPlanCompiler.kt
index d3c91a3a..97e9d6b7 100644
--- a/infrastructure/workflow/src/main/kotlin/com/correx/infrastructure/workflow/ExecutionPlanCompiler.kt
+++ b/infrastructure/workflow/src/main/kotlin/com/correx/infrastructure/workflow/ExecutionPlanCompiler.kt
@@ -66,6 +66,25 @@ class ExecutionPlanCompiler(
         }.toSet()
 
         val start = StageId(plan.stages.first().id)
+        // A declared stage with no path from start can never run — typical LLM topology
+        // failure: every stage wired straight to "done" instead of chained, which silently
+        // truncates the plan to its first stage.
+        val reachable = mutableSetOf(start.value)
+        var frontier = setOf(start.value)
+        while (frontier.isNotEmpty()) {
+            frontier = transitions
+                .filter { it.from.value in frontier }
+                .map { it.to.value }
+                .filter { it != TERMINAL && reachable.add(it) }
+                .toSet()
+        }
+        val unreachable = declared - reachable
+        if (unreachable.isNotEmpty()) {
+            throw WorkflowValidationException(
+                "stages unreachable from start '${start.value}': ${unreachable.sorted().joinToString(", ")} — " +
+                    "chain stages with edges instead of pointing every stage to 'done'",
+            )
+        }
         return WorkflowGraph(id = workflowId, stages = stageMap, transitions = transitions, start = start)
     }
 }
diff --git a/infrastructure/workflow/src/test/kotlin/com/correx/infrastructure/workflow/ExecutionPlanCompilerTest.kt b/infrastructure/workflow/src/test/kotlin/com/correx/infrastructure/workflow/ExecutionPlanCompilerTest.kt
index f054e1d2..0eb21285 100644
--- a/infrastructure/workflow/src/test/kotlin/com/correx/infrastructure/workflow/ExecutionPlanCompilerTest.kt
+++ b/infrastructure/workflow/src/test/kotlin/com/correx/infrastructure/workflow/ExecutionPlanCompilerTest.kt
@@ -129,6 +129,51 @@ class ExecutionPlanCompilerTest {
         assertThrows<WorkflowValidationException> { compiler.compile(plan, "bad-workflow") }
     }
 
+    @Test
+    fun `plan with unreachable stages throws WorkflowValidationException`() {
+        // Live repro (2026-06-12): the architect wired every stage straight to "done"
+        // instead of chaining, so the workflow completed after stage 1 of 3.
+        val plan = """
+            {
+              "goal": "create three files",
+              "stages": [
+                { "id": "create_1", "prompt": "p1", "produces": "f1", "kind": "file_written" },
+                { "id": "create_2", "prompt": "p2", "produces": "f2", "kind": "file_written" },
+                { "id": "create_3", "prompt": "p3", "produces": "f3", "kind": "file_written" }
+              ],
+              "edges": [
+                { "from": "create_1", "to": "done", "condition": { "type": "artifact_validated", "artifact_id": "f1" } },
+                { "from": "create_2", "to": "done", "condition": { "type": "artifact_validated", "artifact_id": "f2" } },
+                { "from": "create_3", "to": "done", "condition": { "type": "artifact_validated", "artifact_id": "f3" } }
+              ]
+            }
+        """.trimIndent()
+        val ex = assertThrows<WorkflowValidationException> { compiler.compile(plan, "bad-workflow") }
+        assertEquals(true, ex.message?.contains("unreachable"))
+    }
+
+    @Test
+    fun `chained plan with single terminal edge compiles`() {
+        val plan = """
+            {
+              "goal": "create three files",
+              "stages": [
+                { "id": "create_1", "prompt": "p1", "produces": "f1", "kind": "file_written" },
+                { "id": "create_2", "prompt": "p2", "produces": "f2", "kind": "file_written" },
+                { "id": "create_3", "prompt": "p3", "produces": "f3", "kind": "file_written" }
+              ],
+              "edges": [
+                { "from": "create_1", "to": "create_2", "condition": { "type": "artifact_validated", "artifact_id": "f1" } },
+                { "from": "create_2", "to": "create_3", "condition": { "type": "artifact_validated", "artifact_id": "f2" } },
+                { "from": "create_3", "to": "done", "condition": { "type": "artifact_validated", "artifact_id": "f3" } }
+              ]
+            }
+        """.trimIndent()
+        val graph = compiler.compile(plan, "chained-workflow")
+        assertEquals(3, graph.stages.size)
+        assertEquals("create_1", graph.start.value)
+    }
+
     @Test
     fun `empty stages throws WorkflowValidationException`() {
         val bad = """{ "goal": "x", "stages": [], "edges": [] }"""