fix(ci): unblock MSRV linux + windows tests for v0.2.5

Two pre-existing CI breakages that have kept main red since 2026-05-06,
both surfaced again on the v0.2.5 push.

MSRV (rust 1.83) — failed to parse rmcp-macros 0.3.2 manifest:
  feature `edition2024` is required (stabilized in Rust 1.85).
Pin rmcp-macros = "=0.3.1" in tj-mcp; cargo update -p rmcp-macros
downgrades rmcp 0.3.2 → 0.3.1 in lockfile. Project tracks rmcp 0.3
line, so this is a within-line constraint, not an API regression.

Windows tests — every JsonlWriter-backed test panicked with:
  acquire exclusive file lock — Access is denied (os error 5)
fd_lock's LockFileEx requires GENERIC_READ on the handle. The file
was opened with create+append only, which gives FILE_APPEND_DATA but
not GENERIC_READ, so the lock failed on Windows. Linux's flock has
no such requirement, so the issue was invisible on POSIX.
Adding read(true) to OpenOptions gives the right access mask
without changing append semantics.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: Shahinyanm

CHANGELOG.md

@@ -34,6 +34,15 @@ no more manual `bashrc` / `settings.json` edits to use `aimux`, `direnv`,
   interactive bash, so the env var was invisible to the classifier
   and 401s kept piling up in `pending/`. The `--classifier-command`
   flag closes that loop end-to-end.
+- CI: pinned `rmcp-macros` to `=0.3.1` so MSRV (Rust 1.83) builds
+  again. `rmcp-macros 0.3.2` requires the `edition2024` Cargo
+  feature, stabilized only in Rust 1.85+. Re-evaluate when MSRV is
+  raised.
+- CI: opened the JSONL append handle with `read(true)` in addition
+  to `append(true)`. `fd_lock`'s `LockFileEx` on Windows requires
+  GENERIC_READ access on the handle; without it tests panicked with
+  `acquire exclusive file lock — Access is denied (os error 5)`.
+  Linux's `flock` was unaffected, so the issue was Windows-only.
 
 ## [0.2.4] - 2026-05-07
 

Cargo.lock

@@ -26,8 +26,15 @@ impl JsonlWriter {
         if let Some(parent) = path.parent() {
             std::fs::create_dir_all(parent).with_context(|| format!("create dir {parent:?}"))?;
         }
+        // `read(true)` is required on Windows: `fd_lock` calls
+        // `LockFileEx` on the underlying handle, which fails with
+        // `os error 5 (Access is denied)` if the file was opened
+        // append-only — the API needs GENERIC_READ access on the
+        // handle. Linux's flock() doesn't care, so the omission was
+        // silent on POSIX. See windows-rs / fd_lock notes.
         let file = OpenOptions::new()
             .create(true)
+            .read(true)
             .append(true)
             .open(&path)
             .with_context(|| format!("open {path:?} for append"))?;

crates/tj-core/src/storage.rs

@@ -22,6 +22,10 @@ tokio = { workspace = true }
 tracing = { workspace = true }
 tracing-subscriber = { workspace = true }
 rmcp = { workspace = true }
+# Pin rmcp-macros to a version compiled with edition 2021 — 0.3.2 requires
+# `edition2024`, stabilized only in Rust 1.85, which breaks our MSRV (1.83).
+# Re-evaluate when MSRV is bumped to ≥1.85.
+rmcp-macros = "=0.3.1"
 serde = { workspace = true }
 serde_json = { workspace = true }
 schemars = { workspace = true }