fix(ffi): Zig 0.15.2 compatibility for 8 new cartridges

- vault-mcp: Replace ArrayList.init() with fixed-size buffer
- discord/telegram/matrix-mcp: Remove discarded unbounded for counters
- gitlab-api-mcp: Fix &mut → & (Zig syntax, not Rust)
- postgresql/redis/mongodb-mcp: Remove linkSystemLibrary for
  uninstalled libs (stub-only builds)

All 36 cartridge FFI shared libraries now build cleanly.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: hyperpolymath

cartridges/discord-mcp/ffi/discord_mcp_ffi.zig

@@ -358,7 +358,7 @@ test "slot exhaustion" {
     discord_mcp_reset();
 
     var slots: [MAX_SESSIONS]c_int = undefined;
-    for (&slots, 0..) |*s, _| {
+    for (&slots) |*s| {
         s.* = discord_mcp_session_open();
         try std.testing.expect(s.* >= 0);
     }

cartridges/gitlab-api-mcp/ffi/gitlab_api_mcp_ffi.zig

@@ -143,7 +143,7 @@ pub export fn gitlab_api_mcp_session_open() c_int {
     mutex.lock();
     defer mutex.unlock();
 
-    for (&mut sessions, 0..) |*slot, idx| {
+    for (&sessions, 0..) |*slot, idx| {
         if (!slot.active) {
             slot.* = .{};
             slot.active = true;
@@ -562,7 +562,7 @@ pub export fn gitlab_api_mcp_logout(slot_idx: c_int) c_int {
 pub export fn gitlab_api_mcp_reset() void {
     mutex.lock();
     defer mutex.unlock();
-    for (&mut sessions) |*slot| {
+    for (&sessions) |*slot| {
         @memset(&slot.token_buf, 0);
     }
     sessions = [_]SessionSlot{.{}} ** MAX_SESSIONS;
@@ -751,7 +751,7 @@ test "slot exhaustion" {
     gitlab_api_mcp_reset();
 
     var slots: [MAX_SESSIONS]c_int = undefined;
-    for (&mut slots) |*s| {
+    for (&slots) |*s| {
         s.* = gitlab_api_mcp_session_open();
         try std.testing.expect(s.* >= 0);
     }

cartridges/jira-mcp/tests/integration_test.sh

@@ -20,7 +20,7 @@ cd "$FFI_DIR" && zig build test 2>&1
 # Validate Idris2 ABI (if idris2 available)
 echo "[3/3] Checking ABI..."
 if command -v idris2 &>/dev/null; then
-    cd "$CART_DIR/abi" && idris2 --check JiraMcp.SafeCloud 2>&1
+    cd "$CART_DIR/abi" && idris2 --check jira_mcp.ipkg 2>&1
     echo "  ABI: OK"
 else
     echo "  ABI: SKIPPED (idris2 not in PATH)"

cartridges/linear-mcp/tests/integration_test.sh

@@ -20,7 +20,7 @@ cd "$FFI_DIR" && zig build test 2>&1
 # Validate Idris2 ABI (if idris2 available)
 echo "[3/3] Checking ABI..."
 if command -v idris2 &>/dev/null; then
-    cd "$CART_DIR/abi" && idris2 --check LinearMcp.SafeCloud 2>&1
+    cd "$CART_DIR/abi" && idris2 --check linear_mcp.ipkg 2>&1
     echo "  ABI: OK"
 else
     echo "  ABI: SKIPPED (idris2 not in PATH)"

cartridges/matrix-mcp/ffi/matrix_mcp_ffi.zig

@@ -376,7 +376,7 @@ test "slot exhaustion" {
     matrix_mcp_reset();
 
     var slots: [MAX_SESSIONS]c_int = undefined;
-    for (&slots, 0..) |*s, _| {
+    for (&slots) |*s| {
         s.* = matrix_mcp_session_open();
         try std.testing.expect(s.* >= 0);
     }

cartridges/mongodb-mcp/ffi/build.zig

@@ -26,8 +26,9 @@ pub fn build(b: *std.Build) void {
         .linkage = .dynamic,
     });
     lib.linkLibC();
-    lib.linkSystemLibrary("mongoc-1.0");
-    lib.linkSystemLibrary("bson-1.0");
+    // NOTE: linkSystemLibrary("mongoc-1.0") and linkSystemLibrary("bson-1.0")
+    // removed — stub implementation does not actually call libmongoc/libbson yet.
+    // Will be re-enabled when real bindings are wired.
     b.installArtifact(lib);
 
     // Tests

cartridges/notion-mcp/tests/integration_test.sh

@@ -20,7 +20,7 @@ cd "$FFI_DIR" && zig build test 2>&1
 # Validate Idris2 ABI (if idris2 available)
 echo "[3/3] Checking ABI..."
 if command -v idris2 &>/dev/null; then
-    cd "$CART_DIR/abi" && idris2 --check NotionMcp.SafeComms 2>&1
+    cd "$CART_DIR/abi" && idris2 --check notion_mcp.ipkg 2>&1
     echo "  ABI: OK"
 else
     echo "  ABI: SKIPPED (idris2 not in PATH)"

cartridges/postgresql-mcp/ffi/build.zig

@@ -26,7 +26,8 @@ pub fn build(b: *std.Build) void {
         .linkage = .dynamic,
     });
     lib.linkLibC();
-    lib.linkSystemLibrary("pq");
+    // NOTE: linkSystemLibrary("pq") removed — stub implementation does not
+    // actually call libpq yet. Will be re-enabled when real bindings are wired.
     b.installArtifact(lib);
 
     // Tests

cartridges/redis-mcp/ffi/build.zig

@@ -26,7 +26,8 @@ pub fn build(b: *std.Build) void {
         .linkage = .dynamic,
     });
     lib.linkLibC();
-    lib.linkSystemLibrary("hiredis");
+    // NOTE: linkSystemLibrary("hiredis") removed — stub implementation does not
+    // actually call hiredis yet. Will be re-enabled when real bindings are wired.
     b.installArtifact(lib);
 
     // Tests

cartridges/telegram-mcp/ffi/telegram_mcp_ffi.zig

@@ -359,7 +359,7 @@ test "slot exhaustion" {
     telegram_mcp_reset();
 
     var slots: [MAX_SESSIONS]c_int = undefined;
-    for (&slots, 0..) |*s, _| {
+    for (&slots) |*s| {
         s.* = telegram_mcp_session_open();
         try std.testing.expect(s.* >= 0);
     }