fix(minimald): lead the shell-exit prompt with the files changed since activation - #1123

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

crates/minimald/src/session_delta.rs (2)

99-141: 🚀 Performance & Scalability | 🔵 Trivial | ⚡ Quick win

Consider excluding build/VCS directories from the walk.

The prior review comment about following directory symlinks is resolved: walkdir's default follow_links(false) means entry.file_type().is_dir() at Line 109 never descends into a symlinked directory, and entry.metadata() at Line 114 returns the symlink's own metadata rather than the target's. Verified both behaviors against the walkdir API docs.

One practical concern remains. WalkDir::new(root) at Line 107 has no entry filtering. For a typical Rust or JS workspace, this walks (and, for files under DIGEST_CAP_BYTES, hashes) every entry under target/, .git/, or node_modules/ as well. Those directories can hold tens of thousands of files, which risks exceeding WALK_TIMEOUT (5 seconds) on exactly the active development workspaces this feature targets — degrading it to "detection disabled" most of the time.

Filter out common heavy, non-source directories (or switch to the ignore crate, as suggested in review), so the timeout stays meaningful for real workspaces.

♻️ Example: skip known heavy directories during the walk

 fn snapshot(root: &Path) -> std::io::Result<Snapshot> {
     let mut out = Snapshot::new();
-    for entry in WalkDir::new(root) {
+    for entry in WalkDir::new(root).into_iter().filter_entry(|e| {
+        e.depth() == 0
+            || !matches!(e.file_name().to_str(), Some(".git" | "target" | "node_modules"))
+    }) {
         let entry = entry?;

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@crates/minimald/src/session_delta.rs` around lines 99 - 141, Update snapshot
to prune common heavy non-source directories such as target, .git, and
node_modules while walking, using WalkDir’s directory filtering/pruning
mechanism so their descendants are never visited or hashed. Preserve existing
symlink-safe traversal and snapshot behavior for all remaining entries.

---

64-97: 📐 Maintainability & Code Quality | 🔵 Trivial | ⚡ Quick win

Log timeout and error paths for diagnosability.

arm and changed_files both resolve the two prior review comments about bounding the walk with WALK_TIMEOUT. Based on learnings, this correctly keeps the filesystem walk on the blocking pool and bounds the .await.

One gap remains: on timeout, I/O error, or panic, both methods silently return None. Nothing signals which case occurred. If a workspace mount wedges in production, this becomes hard to diagnose from logs alone.

Add a tracing::warn! (or debug!) call at each None-producing path, noting the cause (timeout vs. I/O error vs. panic).

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@crates/minimald/src/session_delta.rs` around lines 64 - 97, Update
DeltaSource::arm and DeltaSource::changed_files to log each failure before
returning None, distinguishing timeout, snapshot I/O errors, and spawned-task
panics. Preserve the existing timeout and Option-based control flow while adding
tracing::warn! or debug! messages with the relevant workspace context and error
details where available.

Source: Learnings