feat(context): static-doc compression — prune CLAUDE.md/AGENTS.md doc entries

The big win the pipeline missed: projectProfile + agentInstructions doc dumps
(~14k chars) are L0-SYSTEM -> STATIC -> never pruned, re-sent verbatim every turn.
Now pruned via the same TokenPruner at a gentler ratio (keep 60% vs 45% freeform),
protected spans (code fences/paths/keys) kept so directives survive. Gated by
TOKEN_PRUNE (level 3+); base systemPrompt stays verbatim.

core/context/src/main/kotlin/com/correx/core/context/builder/DefaultContextPackBuilder.kt

@@ -51,7 +51,13 @@ class DefaultContextPackBuilder(
         const val CHARS_PER_TOKEN = 4
         const val FACT_SHEET_ORDINAL = -1
         const val DEFAULT_PRUNE_RATIO = 0.45
+        const val DOC_PRUNE_RATIO = 0.6
+        const val DOC_MIN_CHARS = 1200
         const val TIER0_TURNS = 3
+        // Large static instruction docs (CLAUDE.md project profile, AGENTS.md / DOX framework)
+        // injected verbatim every turn. Pruned at DOC_PRUNE_RATIO — gentler than freeform, with
+        // protected spans (code fences, paths, config keys) kept, so directives survive.
+        val DOC_SOURCE_TYPES = setOf("projectProfile", "agentInstructions")
     }
 
     override suspend fun build(
@@ -142,10 +148,18 @@ class DefaultContextPackBuilder(
             .map { it.ordinal }.sortedDescending()
         val tier0 = if (tierSplit) freeformOrdinals.take(TIER0_TURNS).toSet() else emptySet()
         return entries.map { entry ->
-            if (classifier.classify(entry) != ContextClass.FREEFORM || entry.ordinal in tier0) entry
-            else reencode(entry, tokenPruner.prune(entry.content, tagger.protectedSpans(entry.content), DEFAULT_PRUNE_RATIO))
+            val isFreeform = classifier.classify(entry) == ContextClass.FREEFORM && entry.ordinal !in tier0
+            val isLargeDoc = entry.sourceType in DOC_SOURCE_TYPES && entry.content.length >= DOC_MIN_CHARS
+            when {
+                isFreeform -> reencode(entry, tokenPruner.prune(entry.content, spansOf(entry), DEFAULT_PRUNE_RATIO))
+                // Static instruction docs: gentler ratio so directives survive the classifier.
+                isLargeDoc -> reencode(entry, tokenPruner.prune(entry.content, spansOf(entry), DOC_PRUNE_RATIO))
+                else -> entry
             }
         }
+    }
+
+    private fun spansOf(entry: ContextEntry) = tagger.protectedSpans(entry.content)
 
     private fun applyToMe(entries: List<ContextEntry>): List<ContextEntry> {
         val (freeform, rest) = entries.partition { classifier.classify(it) == ContextClass.FREEFORM }

core/context/src/test/kotlin/CompressionPipelineStagesTest.kt

@@ -137,6 +137,28 @@ class CompressionPipelineStagesTest {
         Unit
     }
 
+    @Test
+    fun `large static doc entries are pruned at level 3 while base system prompt is untouched`() = kotlinx.coroutines.runBlocking {
+        val pruner = object : com.correx.core.context.compression.TokenPruner {
+            override suspend fun prune(content: String, protectedSpans: List<String>, targetRatio: Double): String = "DOC-PRUNED"
+        }
+        val builder = com.correx.core.context.builder.DefaultContextPackBuilder(
+            com.correx.core.context.compression.DefaultContextCompressor(), CompressionPolicy(3), tokenPruner = pruner,
+        )
+        val bigDoc = "# CLAUDE.md\n" + "guidance line ".repeat(120) // > DOC_MIN_CHARS
+        val entries = listOf(
+            entry("proj", ContextLayer.L0, EntryRole.SYSTEM, bigDoc).copy(sourceType = "projectProfile"),
+            entry("sys", ContextLayer.L0, EntryRole.SYSTEM, "you are an agent").copy(sourceType = "systemPrompt"),
+        )
+        val flat = builder.build(
+            com.correx.core.events.types.ContextPackId("p"), com.correx.core.events.types.SessionId("s"),
+            com.correx.core.events.types.StageId("st"), entries, com.correx.core.context.model.TokenBudget(limit = 4000),
+        ).layers.values.flatten()
+        assertEquals("DOC-PRUNED", flat.first { it.sourceType == "projectProfile" }.content)
+        assertEquals("you are an agent", flat.first { it.sourceType == "systemPrompt" }.content)
+        Unit
+    }
+
     @Test
     fun `classifier separates static structured freeform`() {
         val c = ContextClassifier()