ffi 2.6 green: #jni_method_descriptor("(Sig)Ret") override

New `hash_jni_method_descriptor` lexer token + LSP keyword
classification. `JniMethodDecl` gains `desc_override: ?[]const u8`.
parseJniClassDecl accepts an optional `#jni_method_descriptor("...")`
clause between the return type and the terminating `;`, stashing the
literal as the override. Auto-derivation in Phase 2.8 will treat
this as the precedence override when present.

The 2.6 xfail commit (0ed4799) used the working name `#desc` in its
test file; this commit renames to `#jni_method_descriptor` for
parallel naming with the rest of the FFI directive set (`#jni_call`,
`#jni_class`, `#jni_env`, ...). Test snapshot flips xfail → green.

125/125 examples green.

examples/ffi-jni-class-06-desc.sx

@@ -1,17 +1,17 @@
 // Phase 2 step 2.6 (PLAN-FFI.md): xfail then green for the
-// `#desc("(Sig)Ret")` per-method JNI-descriptor override.
+// `#jni_method_descriptor("(Sig)Ret")` per-method JNI-descriptor
+// override.
 //
-// The default descriptor is derived from sx types (Phase 2.8); `#desc`
-// is the escape hatch when the auto-derived signature doesn't match
-// (e.g., synthetic methods, ambiguous overloads, accessing JNI
-// internals). It appears trailing the method's return type, before
-// the terminating `;`. Today the parser expects `;` immediately after
-// the return type and errors at the `#desc` token.
+// The default descriptor is derived from sx types (Phase 2.8); this
+// directive is the escape hatch when the auto-derived signature
+// doesn't match (e.g., synthetic methods, ambiguous overloads,
+// accessing JNI internals). It appears trailing the method's return
+// type, before the terminating `;`.
 
 #import "modules/std.sx";
 
 Foo :: #jni_class("com/example/Foo") {
-    weirdMethod :: (self: *Self) -> s32 #desc("()I");
+    weirdMethod :: (self: *Self) -> s32 #jni_method_descriptor("()I");
 }
 
 main :: () -> s32 {

src/ast.zig

@@ -539,6 +539,7 @@ pub const JniMethodDecl = struct {
     param_names: []const []const u8,
     return_type: ?*Node, // null = void
     is_static: bool = false, // true for `static name :: ...`
+    desc_override: ?[]const u8 = null, // `#desc("(Sig)Ret")` — skips auto-derivation in 2.8+
 };
 
 pub const JniFieldDecl = struct {

src/lexer.zig

@@ -85,6 +85,7 @@ pub const Lexer = struct {
                 .{ "#jni_class", Tag.hash_jni_class },
                 .{ "#extends", Tag.hash_extends },
                 .{ "#implements", Tag.hash_implements },
+                .{ "#jni_method_descriptor", Tag.hash_jni_method_descriptor },
             };
             inline for (directives) |d| {
                 const keyword = d[0];

src/lsp/server.zig

@@ -1501,6 +1501,7 @@ pub const Server = struct {
             .hash_jni_class,
             .hash_extends,
             .hash_implements,
+            .hash_jni_method_descriptor,
             => ST.keyword,
 
             .kw_f32, .kw_f64, .kw_Type, .kw_Self => ST.type_,

src/parser.zig

@@ -1121,6 +1121,20 @@ pub const Parser = struct {
                 return_type = try self.parseTypeExpr();
             }
 
+            // Optional `#jni_method_descriptor("(Sig)Ret")` — explicit JNI descriptor override.
+            var desc_override: ?[]const u8 = null;
+            if (self.current.tag == .hash_jni_method_descriptor) {
+                self.advance(); // skip `#jni_method_descriptor`
+                try self.expect(.l_paren);
+                if (self.current.tag != .string_literal) {
+                    return self.fail("expected string literal JNI descriptor after '#jni_method_descriptor('");
+                }
+                const raw_desc = self.tokenSlice(self.current);
+                desc_override = raw_desc[1 .. raw_desc.len - 1];
+                self.advance();
+                try self.expect(.r_paren);
+            }
+
             try self.expect(.semicolon);
 
             try members.append(self.allocator, .{ .method = .{
@@ -1129,6 +1143,7 @@ pub const Parser = struct {
                 .param_names = try param_names.toOwnedSlice(self.allocator),
                 .return_type = return_type,
                 .is_static = is_static,
+                .desc_override = desc_override,
             } });
         }
         try self.expect(.r_brace);

src/token.zig

@@ -118,6 +118,7 @@ pub const Tag = enum {
     hash_jni_class, // Foo :: #jni_class("java/path/Foo") { ...body... }
     hash_extends, // `#extends Alias;` inside a #jni_class / #objc_class body
     hash_implements, // `#implements Alias;` inside a #jni_class / #objc_class body
+    hash_jni_method_descriptor, // `#jni_method_descriptor("(Sig)Ret")` per-method JNI descriptor override
     triple_minus, // ---
 
     // Special

tests/expected/ffi-jni-class-06-desc.exit

@@ -1 +1 @@
-1
+0

tests/expected/ffi-jni-class-06-desc.txt

@@ -1 +1 @@
-/Users/agra/projects/sx/examples/ffi-jni-class-06-desc.sx:14:41: error: expected ';'
+parse-only ok