feat: Wave 1 complete — state machine, Paseo hub, collision detection, PTY search

- Task state machine: TIMED_OUT state, retriable steps, timeout detection
- Paseo hub: paseo-client.ts (HTTP+CLI), PaseoBackend (AgentBackend), 14 tests
- Collision detection: collision-detector.ts, conflict-index.ts, ws-frames type
- PTY search: ring buffer, search route, capture-pane fallback

apps/coder/src/services/collision-detector.ts

@@ -0,0 +1,115 @@
+// v2.8 Collision detection — pure functions that find file overlaps between
+// worktrees/agents editing the same files concurrently. Advisory only; writes
+// are never blocked, but the collision info surfaces in the UI and logs.
+//
+// Severity levels:
+//   same_line     — the same file, exact same line region
+//   adjacent_line — the same file, lines touch or are within 5 lines
+//   different_area — the same file, distant lines
+//
+// Pure functions, no side effects. Testable in isolation.
+
+export type ConflictSeverity = 'same_line' | 'adjacent_line' | 'different_area';
+
+export interface ConflictVerdict {
+  filePath: string;
+  worktrees: string[];
+  severity: ConflictSeverity;
+  agents: string[];
+}
+
+/**
+ * Registry entry for a single file change recorded by a worktree.
+ * Stored in the ConflictIndex Map value for each file path.
+ */
+export interface ConflictEntry {
+  worktreeId: string;
+  agent: string;
+  /**
+   * Approximate line range touched by the change. undefined when the change
+   * creates or deletes the file (full-file collision vs. same-line).
+   */
+  lineRange?: { start: number; end: number };
+  status: 'pending' | 'applied' | 'reverted';
+  timestamp: number;
+}
+
+/**
+ * Shape of the conflict index consumed by findConflicts.
+ * File path → set of entries from different worktrees/agents.
+ */
+export type ConflictIndexData = ReadonlyMap<string, ReadonlySet<ConflictEntry>>;
+
+/**
+ * Find file overlaps between `changedFiles` and the conflict index, excluding
+ * the caller's own worktree.
+ *
+ * Returns one ConflictVerdict per file that has entries from other worktrees.
+ * Severity is the highest found (same_line > adjacent_line > different_area).
+ */
+export function findConflicts(
+  changedFiles: string[],
+  worktreeId: string,
+  /** Approximate line range for the proposed changes, keyed by file path */
+  changedRanges: Map<string, { start: number; end: number }>,
+  conflictIndex: ConflictIndexData,
+): ConflictVerdict[] {
+  const verdicts: ConflictVerdict[] = [];
+
+  for (const filePath of changedFiles) {
+    const entries = conflictIndex.get(filePath);
+    if (!entries || entries.size === 0) continue;
+
+    // Filter to entries from OTHER worktrees
+    const otherEntries = [...entries].filter((e) => e.worktreeId !== worktreeId);
+    if (otherEntries.length === 0) continue;
+
+    const myRange = changedRanges.get(filePath);
+    let severity: ConflictSeverity = 'different_area';
+
+    for (const entry of otherEntries) {
+      if (!myRange || !entry.lineRange) {
+        // Full-file changes (create/delete) always hit at least different_area
+        continue;
+      }
+      const sev = lineOverlapSeverity(myRange, entry.lineRange);
+      if (sev === 'same_line') {
+        severity = 'same_line';
+        break; // Can't get higher than this
+      }
+      if (sev === 'adjacent_line' && severity === 'different_area') {
+        severity = 'adjacent_line';
+      }
+    }
+
+    const worktrees = [...new Set(otherEntries.map((e) => e.worktreeId))];
+    const agents = [...new Set(otherEntries.map((e) => e.agent))];
+
+    verdicts.push({ filePath, worktrees, severity, agents });
+  }
+
+  return verdicts;
+}
+
+const ADJACENT_LINE_THRESHOLD = 5;
+
+/**
+ * Determine severity of overlap between two line ranges.
+ */
+function lineOverlapSeverity(
+  a: { start: number; end: number },
+  b: { start: number; end: number },
+): ConflictSeverity {
+  // Same_line: ranges intersect
+  if (a.start <= b.end && b.start <= a.end) {
+    return 'same_line';
+  }
+
+  // Adjacent: ranges are within ADJACENT_LINE_THRESHOLD lines of each other
+  const gap = a.start > b.end ? a.start - b.end : b.start - a.end;
+  if (gap <= ADJACENT_LINE_THRESHOLD) {
+    return 'adjacent_line';
+  }
+
+  return 'different_area';
+}