feat(memory): markdown heading extraction in RepoMapIndexer

h1-h3 headings become the file's symbols, so design docs and GDDs are
embedded and retrievable alongside code. .md files now also participate in
workspace fingerprinting (INDEXED_EXTENSIONS derives from pattern keys).

apps/server/src/main/kotlin/com/correx/apps/server/memory/RepoMapIndexer.kt

@@ -84,6 +84,8 @@ class RepoMapIndexer(
             "ts" to Regex("""(?m)^\s*(?:export\s+)?(?:default\s+)?(?:async\s+)?(?:function|class|interface|type|enum)\s+(?<name>[A-Za-z_$][A-Za-z0-9_$]*)"""),
             // GDScript: column-0 declarations only, so indented inner-class members never match.
             "gd" to Regex("""(?m)^(?:static\s+)?(?:func|class_name|class|signal|enum)\s+(?<name>[A-Za-z_][A-Za-z0-9_]*)"""),
+            // Markdown: h1–h3 headings as "symbols" — deeper levels are noise relative to retrieval value.
+            "md" to Regex("""(?m)^#{1,3}\s+(?<name>.+?)\s*$"""),
         )
     }
 }

apps/server/src/test/kotlin/com/correx/apps/server/memory/RepoMapIndexerTest.kt

@@ -23,7 +23,7 @@ class RepoMapIndexerTest {
         root.resolve("build/Generated.kt").writeText("class Generated\n")
 
         // Non-source file must be ignored.
-        root.resolve("README.md").writeText("# hi\n")
+        root.resolve("notes.txt").writeText("scratch\n")
 
         val entries = RepoMapIndexer(maxDepth = 4, ignoreGlobs = listOf("build")).index(root)
 
@@ -31,7 +31,7 @@ class RepoMapIndexerTest {
         assertTrue(paths.contains("New.kt"))
         assertTrue(paths.contains("Old.kt"))
         assertFalse(paths.any { it.contains("build") }, "ignored dir leaked: $paths")
-        assertFalse(paths.contains("README.md"), "non-source file leaked")
+        assertFalse(paths.contains("notes.txt"), "non-source file leaked")
 
         // Most-recently-modified ranks first.
         assertEquals("New.kt", entries.first().path)
@@ -75,6 +75,30 @@ class RepoMapIndexerTest {
         assertFalse(entry.symbols.contains("help"), "indented inner method must not be matched")
     }
 
+    @Test
+    fun `extracts markdown headings as symbols`(@TempDir root: Path) {
+        root.resolve("design.md").writeText(
+            """
+            # Game Design Document
+            intro text with an inline # hash
+
+            ## Combat System
+            body
+
+            ### Damage Formula
+            #### Too Deep To Matter
+            """.trimIndent(),
+        )
+
+        val entry = RepoMapIndexer().index(root).single()
+        assertEquals("design.md", entry.path)
+        assertTrue(
+            entry.symbols.containsAll(listOf("Game Design Document", "Combat System", "Damage Formula")),
+            "missing headings in: ${entry.symbols}",
+        )
+        assertFalse(entry.symbols.any { it.contains("Too Deep") }, "h4+ headings must not be matched")
+    }
+
     @Test
     fun `empty or missing root yields empty map`(@TempDir root: Path) {
         assertTrue(RepoMapIndexer().index(root).isEmpty())