feat(journal): ProjectMemoryDistiller — pure repo-scoped decision distillation

core/journal/src/main/kotlin/com/correx/core/journal/ProjectMemoryDistiller.kt

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+package com.correx.core.journal
+
+import com.correx.core.journal.model.DecisionJournalState
+
+/**
+ * Distils a decision journal into durable, repo-scoped memory lines for persistence to the
+ * cross-session L3 store. Pure transform (no I/O) so `core:journal` stays dependent only on
+ * `core:events`; the actual L3 upsert/retrieve lives in the wiring layer that owns the store.
+ *
+ * Each line is namespaced by [repoRoot] so retrieval can attribute a decision to its project.
+ */
+class ProjectMemoryDistiller(private val keepLast: Int = 40) {
+    fun distill(state: DecisionJournalState, repoRoot: String): List<String> =
+        state.records.takeLast(keepLast).map { "[$repoRoot] [${it.kind}] ${it.summary}" }
+}

testing/projections/src/test/kotlin/ProjectMemoryDistillerTest.kt

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+import com.correx.core.journal.ProjectMemoryDistiller
+import com.correx.core.journal.model.DecisionJournalState
+import com.correx.core.journal.model.DecisionKind
+import com.correx.core.journal.model.DecisionRecord
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Assertions.assertTrue
+import org.junit.jupiter.api.Test
+
+class ProjectMemoryDistillerTest {
+
+    @Test
+    fun `distils records into repo-namespaced lines`() {
+        val state = DecisionJournalState(
+            records = listOf(
+                DecisionRecord(1, DecisionKind.STEERING, "User steering: use jwt"),
+                DecisionRecord(2, DecisionKind.TRANSITION, "Advanced plan → impl (t1)"),
+            ),
+        )
+        val lines = ProjectMemoryDistiller().distill(state, "/home/me/repo")
+
+        assertEquals(2, lines.size)
+        assertEquals("[/home/me/repo] [STEERING] User steering: use jwt", lines[0])
+        assertTrue(lines[1].startsWith("[/home/me/repo] [TRANSITION]"))
+    }
+
+    @Test
+    fun `keepLast bounds the distilled output`() {
+        val records = (1..50).map { DecisionRecord(it.toLong(), DecisionKind.ARTIFACT, "v$it") }
+        val lines = ProjectMemoryDistiller(keepLast = 10).distill(DecisionJournalState(records), "/r")
+
+        assertEquals(10, lines.size)
+        assertTrue(lines.last().contains("v50"))
+        assertTrue(lines.first().contains("v41"))
+    }
+}