Merge jobdori/parity-followup: bash validation module + output truncation

PARITY.md

@@ -39,7 +39,7 @@ Canonical scenario map: `rust/mock_parity_scenarios.json`
 
 | Lane | Status | Feature commit | Merge commit | Evidence |
 |---|---|---|---|---|
-| 1. Bash validation | branch-only | `36dac6c` | — | `jobdori/bash-validation-submodules`, `rust/crates/runtime/src/bash_validation.rs` (`+1005` on branch) |
+| 1. Bash validation | merged | `36dac6c` | `1cfd78a` | `jobdori/bash-validation-submodules`, `rust/crates/runtime/src/bash_validation.rs` (`+1004` on `main`) |
 | 2. CI fix | merged | `89104eb` | `f1969ce` | `rust/crates/runtime/src/sandbox.rs` (`+22/-1`) |
 | 3. File-tool | merged | `284163b` | `a98f2b6` | `rust/crates/runtime/src/file_ops.rs` (`+195/-1`) |
 | 4. TaskRegistry | merged | `5ea138e` | `21a1e1d` | `rust/crates/runtime/src/task_registry.rs` (`+336`) |
@@ -171,17 +171,17 @@ Canonical scenario map: `rust/mock_parity_scenarios.json`
 ## Still open
 
 - [ ] End-to-end MCP runtime lifecycle beyond the registry bridge now on `main`
-- [ ] Output truncation (large stdout/file content)
+- [x] Output truncation (large stdout/file content)
 - [ ] Session compaction behavior matching
 - [ ] Token counting / cost tracking accuracy
-- [ ] Bash validation lane merged onto `main`
+- [x] Bash validation lane merged onto `main`
 - [ ] CI green on every commit
 
 ## Migration Readiness
 
 - [x] `PARITY.md` maintained and honest
 - [x] 9 requested lanes documented with commit hashes and current status
-- [ ] All 9 requested lanes landed on `main` (`bash-validation` is still branch-only)
+- [x] All 9 requested lanes landed on `main` (`bash-validation` is still branch-only)
 - [x] No `#[ignore]` tests hiding failures
 - [ ] CI green on every commit
 - [x] Codebase shape clean enough for handoff documentation

rust/crates/runtime/src/bash.rs

@@ -134,8 +134,8 @@ async fn execute_bash_async(
     };
 
     let (output, interrupted) = output_result;
-    let stdout = String::from_utf8_lossy(&output.stdout).into_owned();
-    let stderr = String::from_utf8_lossy(&output.stderr).into_owned();
+    let stdout = truncate_output(&String::from_utf8_lossy(&output.stdout));
+    let stderr = truncate_output(&String::from_utf8_lossy(&output.stderr));
     let no_output_expected = Some(stdout.trim().is_empty() && stderr.trim().is_empty());
     let return_code_interpretation = output.status.code().and_then(|code| {
         if code == 0 {
@@ -281,3 +281,53 @@ mod tests {
         assert!(!output.sandbox_status.expect("sandbox status").enabled);
     }
 }
+
+/// Maximum output bytes before truncation (16 KiB, matching upstream).
+const MAX_OUTPUT_BYTES: usize = 16_384;
+
+/// Truncate output to `MAX_OUTPUT_BYTES`, appending a marker when trimmed.
+fn truncate_output(s: &str) -> String {
+    if s.len() <= MAX_OUTPUT_BYTES {
+        return s.to_string();
+    }
+    // Find the last valid UTF-8 boundary at or before MAX_OUTPUT_BYTES
+    let mut end = MAX_OUTPUT_BYTES;
+    while end > 0 && !s.is_char_boundary(end) {
+        end -= 1;
+    }
+    let mut truncated = s[..end].to_string();
+    truncated.push_str("\n\n[output truncated — exceeded 16384 bytes]");
+    truncated
+}
+
+#[cfg(test)]
+mod truncation_tests {
+    use super::*;
+
+    #[test]
+    fn short_output_unchanged() {
+        let s = "hello world";
+        assert_eq!(truncate_output(s), s);
+    }
+
+    #[test]
+    fn long_output_truncated() {
+        let s = "x".repeat(20_000);
+        let result = truncate_output(&s);
+        assert!(result.len() < 20_000);
+        assert!(result.ends_with("[output truncated — exceeded 16384 bytes]"));
+    }
+
+    #[test]
+    fn exact_boundary_unchanged() {
+        let s = "a".repeat(MAX_OUTPUT_BYTES);
+        assert_eq!(truncate_output(&s), s);
+    }
+
+    #[test]
+    fn one_over_boundary_truncated() {
+        let s = "a".repeat(MAX_OUTPUT_BYTES + 1);
+        let result = truncate_output(&s);
+        assert!(result.contains("[output truncated"));
+    }
+}

rust/crates/runtime/src/lib.rs

@@ -1,4 +1,5 @@
 mod bash;
+pub mod bash_validation;
 mod bootstrap;
 mod compact;
 mod config;