feat(context): compression pipeline stage 1 — level policy + deterministic stages

Additive CompressionPolicy (levels 1-9), ProtectedSpanTagger (regex
load-bearing spans), FormatCompressor (json→dotted lines), ContextClassifier
(static/structured/freeform). Stage 1 (FORMAT_COMPRESS) wired into
DefaultContextPackBuilder behind the policy; structured entries only, lossless.
PromptRenderer repetition-anchoring of steering directives.

testing/deterministic/src/test/kotlin/PromptRendererOrderingTest.kt

@@ -70,6 +70,33 @@ class PromptRendererOrderingTest {
         assertEquals(listOf("system" to "memory", "user" to "question"), messages.map { it.role to it.content })
     }
 
+    @Test
+    fun `steering directives are re-anchored as a trailing user reminder`() {
+        // A steering note folds into the leading system block AND is restated at the tail so a
+        // weak local model still sees the active constraint next to the final query.
+        val pack = ContextPack(
+            id = ContextPackId("p"),
+            sessionId = sessionId,
+            stageId = stageId,
+            layers = mapOf(
+                ContextLayer.L0 to listOf(entry("sys", ContextLayer.L0, EntryRole.SYSTEM, "systemPrompt")),
+                ContextLayer.L2 to listOf(entry("directive", ContextLayer.L2, EntryRole.SYSTEM, "steeringNote")),
+                ContextLayer.L1 to listOf(entry("question", ContextLayer.L1, EntryRole.USER, "chat")),
+            ),
+            budgetUsed = 30,
+            budgetLimit = 4000,
+        )
+        val messages = PromptRenderer.render(pack)
+        assertEquals(
+            listOf(
+                "system" to "sys\n\ndirective",
+                "user" to "question",
+                "user" to "Reminder — active steering directive(s):\ndirective",
+            ),
+            messages.map { it.role to it.content },
+        )
+    }
+
     @Test
     fun `non-L0 SYSTEM entries fold into the single leading system message`() {
         // Strict chat templates (Qwen) 400 on any system message after index 0. Recalled L3