Fix edit_file corruption and matching, shell timeout process groups, grep/glob read boundary

internal/agent/learn.go

@@ -104,11 +104,21 @@ func (a *Agent) lessonsBlock(ctx context.Context) string {
 		return ""
 	}
 	var lessons []string
+	seen := make(map[string]struct{})
 	for _, m := range items {
 		if m.Source == lessonSource {
-			lessons = append(lessons, m.Content)
+			lesson := strings.TrimSpace(m.Content)
+			if !usableLesson(lesson) {
+				continue
+			}
+			key := strings.ToLower(lesson)
+			if _, ok := seen[key]; ok {
+				continue
+			}
+			seen[key] = struct{}{}
+			lessons = append(lessons, lesson)
 		}
-		if len(lessons) >= 20 {
+		if len(lessons) >= 12 {
 			break
 		}
 	}
@@ -123,3 +133,20 @@ func (a *Agent) lessonsBlock(ctx context.Context) string {
 	}
 	return b.String()
 }
+
+// usableLesson keeps malformed auxiliary-model output out of the system
+// prompt. Historical rows include fragments such as "NONE", "Wait", and
+// duplicated partial sentences; presenting them as instructions makes tool
+// behavior less predictable and wastes context.
+func usableLesson(s string) bool {
+	if len(s) < 32 || len(s) > 400 {
+		return false
+	}
+	if strings.EqualFold(s, "none") || strings.HasSuffix(strings.ToLower(s), " none") {
+		return false
+	}
+	if strings.EqualFold(s, "wait") || strings.EqualFold(s, ".") {
+		return false
+	}
+	return true
+}

internal/agent/learn_test.go

@@ -0,0 +1,20 @@
+package agent
+
+import "testing"
+
+func TestUsableLessonRejectsAuxiliaryFragments(t *testing.T) {
+	for _, lesson := range []string{"NONE", "Wait", ".", "When `edit_file"} {
+		if usableLesson(lesson) {
+			t.Errorf("malformed lesson accepted: %q", lesson)
+		}
+	}
+	if !usableLesson("When edit_file fails with old_string not found, read the current file and copy exact whitespace before retrying.") {
+		t.Fatal("valid lesson rejected")
+	}
+}
+
+func TestUsableLessonRejectsTrailingNone(t *testing.T) {
+	if usableLesson("When a tool fails, inspect the concrete error and retry with corrected arguments. NONE") {
+		t.Fatal("auxiliary NONE suffix should not enter the prompt")
+	}
+}

internal/agent/prompt.go

@@ -106,6 +106,7 @@ help them now — do not block them.
 			// paste line numbers into old_string or expand tabs to spaces and
 			// the exact match fails repeatedly.
 			b.WriteString("- read_file returns lines as `NUMBER|CONTENT`. The `|` is metadata only. When calling edit_file, copy **only** the content after `|` into old_string/new_string — never the line number. Preserve tabs and spaces exactly (do not expand tabs to spaces). Line endings are matched automatically.\n")
+			b.WriteString("- Before every edit_file call, re-read the region you are editing (read_file with offset/limit on large files). edit_file requires an exact, unique old_string from that fresh read. After any successful edit or write, re-read before making another edit; do not reuse an older block or invent identifiers. If it reports multiple occurrences, include unique neighbouring lines or use replace_all only when every occurrence should change.\n")
 		}
 		if hasTool(active, "vps_upload") || hasTool(active, "vps_download") || hasTool(active, "vps_run") {
 			// Without this, models fall back to terminal rsync/scp and never use

internal/tools/background_process_unix.go

@@ -8,7 +8,16 @@ import (
 )
 
 func configureProcessGroup(cmd *exec.Cmd) {
-	cmd.SysProcAttr = &syscall.SysProcAttr{Setpgid: true}
+	if cmd == nil {
+		return
+	}
+	// Sandboxed commands may already carry Cloneflags, uid mappings, or a
+	// parent-death signal. Preserve those settings while adding the process
+	// group needed to terminate a command tree on timeout.
+	if cmd.SysProcAttr == nil {
+		cmd.SysProcAttr = &syscall.SysProcAttr{}
+	}
+	cmd.SysProcAttr.Setpgid = true
 }
 
 func terminateProcessGroup(cmd *exec.Cmd) {