feat(tasks): cite-before-claim gate on completion

Completing a task that declared affected_paths but saw no matching write this
session is now blocked ("marked done without doing it"), escapable with force.
TaskUpdateTool reads the session's writes through a SessionWrites port whose
adapter folds SessionContext (writes = recorded receipt.affectedEntities), and
matches them against the task's affected_paths globs.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

infrastructure/tools/src/main/kotlin/com/correx/infrastructure/tools/task/SessionWrites.kt

@@ -0,0 +1,13 @@
+package com.correx.infrastructure.tools.task
+
+import com.correx.core.events.types.SessionId
+
+/**
+ * Port: the paths a session has written this run. The host supplies an adapter that folds the
+ * session's SessionContext (its writes come from the recorded receipt.affectedEntities). The
+ * cite-before-claim gate in [TaskUpdateTool] uses it to confirm a task being completed actually saw
+ * changes under its affected_paths. A null binding leaves the gate off.
+ */
+fun interface SessionWrites {
+    fun pathsWritten(sessionId: SessionId): Set<String>
+}

infrastructure/tools/src/main/kotlin/com/correx/infrastructure/tools/task/TaskTools.kt

@@ -22,10 +22,11 @@ object TaskTools {
         artifactResolver: TaskArtifactResolver? = null,
         sessionResolver: TaskSessionResolver? = null,
         sessionFacts: SessionFactRecorder? = null,
+        sessionWrites: SessionWrites? = null,
     ): List<Tool> =
         listOf(
             TaskCreateTool(service),
-            TaskUpdateTool(service, sessionFacts),
+            TaskUpdateTool(service, sessionFacts, sessionWrites),
             TaskDeleteTool(service),
             TaskSearchTool(service),
             TaskReadyTool(service),

infrastructure/tools/src/main/kotlin/com/correx/infrastructure/tools/task/TaskUpdateTool.kt

@@ -20,14 +20,21 @@ import kotlinx.serialization.json.buildJsonArray
 import kotlinx.serialization.json.buildJsonObject
 import kotlinx.serialization.json.put
 import kotlinx.serialization.json.putJsonObject
+import java.nio.file.FileSystems
+import java.nio.file.Path
 
 /**
  * Agent-facing tool: update an existing task — edit fields, transition status, add a work-graph
  * link, or attach a note. The task's project is derived from its id, so only the id is required.
+ *
+ * [sessionFacts] records the session's active task on claim; [sessionWrites], when bound, powers
+ * the cite-before-claim gate (completing a task that declared affected_paths but saw no matching
+ * write this session is blocked, escapable with force).
  */
 class TaskUpdateTool(
     private val service: TaskService,
     private val sessionFacts: SessionFactRecorder? = null,
+    private val sessionWrites: SessionWrites? = null,
 ) : Tool, ToolExecutor {
 
     override val name: String = "task_update"
@@ -95,6 +102,7 @@ class TaskUpdateTool(
 
         val action = request.stringParam("action")
         claimBlock(request, taskId, action)?.let { return it }
+        completeBlock(request, taskId, action)?.let { return it }
 
         applyFieldEdits(request, taskId)
 
@@ -133,6 +141,35 @@ class TaskUpdateTool(
         return fail(request, "Cannot claim ${taskId.value} — unmet blockers: $listed. Complete them, or pass force=true.")
     }
 
+    /**
+     * Cite-before-claim: refuse to complete a task that declared affected_paths but saw no matching
+     * write this session — "marked done without doing it." Off when no [sessionWrites] is bound or
+     * the task declared no scope; escapable with force.
+     */
+    private fun completeBlock(request: ToolRequest, taskId: TaskId, action: String?): ToolResult.Failure? {
+        if (action != "complete" || request.boolParam("force")) return null
+        val writes = sessionWrites ?: return null
+        val scope = service.getTask(taskId)?.state?.affectedPaths.orEmpty()
+        if (scope.isEmpty()) return null
+        if (matchesAnyGlob(writes.pathsWritten(request.sessionId), scope)) return null
+        return fail(
+            request,
+            "Cannot complete ${taskId.value} — no changes under its affected_paths ($scope) this " +
+                "session. Make the change, or pass force=true.",
+        )
+    }
+
+    /** True if any written path matches any affected_paths glob (workspace-relative; './' tolerated). */
+    private fun matchesAnyGlob(written: Set<String>, globs: List<String>): Boolean {
+        if (written.isEmpty()) return false
+        val fs = FileSystems.getDefault()
+        val matchers = globs.map { fs.getPathMatcher("glob:${it.removePrefix("./")}") }
+        return written.any { w ->
+            val rel = Path.of(w.removePrefix("./"))
+            matchers.any { it.matches(rel) }
+        }
+    }
+
     /**
      * Record the session→task working relationship (for SessionContext.activeTask) on a claim, or on
      * an affected_paths edit by the recorded claimant (to refresh the snapshot scope). No-op without

infrastructure/tools/src/test/kotlin/com/correx/infrastructure/tools/task/TaskToolsTest.kt

@@ -228,6 +228,31 @@ class TaskToolsTest {
         assertEquals(listOf("core/auth/**"), captured.single().third)
     }
 
+    @Test
+    fun `task_update blocks completing a task with no writes under its affected_paths`() = runBlocking {
+        create.execute(
+            request(
+                "task_create",
+                mapOf("project" to "auth", "title" to "A", "goal" to "g", "affected_paths" to listOf("core/auth/**")),
+            ),
+        )
+        val id = "auth-1"
+        update.execute(request("task_update", mapOf("id" to id, "action" to "claim")))
+        update.execute(request("task_update", mapOf("id" to id, "action" to "submit_for_review")))
+
+        // No matching write this session → complete is blocked, task stays IN_REVIEW.
+        val noWrites = TaskUpdateTool(service, sessionWrites = SessionWrites { emptySet() })
+        val blocked = noWrites.execute(request("task_update", mapOf("id" to id, "action" to "complete")))
+        assertTrue(blocked is ToolResult.Failure)
+        assertEquals(TaskStatus.IN_REVIEW, service.getTask(TaskId(id))!!.state.status)
+
+        // A write under affected_paths → completes.
+        val withWrites = TaskUpdateTool(service, sessionWrites = SessionWrites { setOf("core/auth/Login.kt") })
+        val ok = withWrites.execute(request("task_update", mapOf("id" to id, "action" to "complete")))
+        assertTrue(ok is ToolResult.Success)
+        assertEquals(TaskStatus.DONE, service.getTask(TaskId(id))!!.state.status)
+    }
+
     @Test
     fun `task_delete tombstones the task`() = runBlocking {
         val id = createTask()