docs(sprints): mark Track C (East Reach) done in copy briefing

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

docs/sprints/sprint-29/copy.md

@@ -18,6 +18,18 @@ Each system follows the `/atlas author-system` pipeline:
 
 See `.claude/skills/atlas/references/author-system.md` for full details.
 
+**STRICT: One system at a time.** Complete the full pipeline (steps 1–7)
+for a single system before starting the next. Do NOT batch systems for
+writing, naming, or review. Batching causes agent context overflow,
+cross-system bleed in review feedback, and review agents getting stuck
+on oversized payloads. Each system must be isolated in the review agents'
+context windows — send one system to Miri, get names back and apply them,
+send to Paula and Ozzie, get reviews back and fix issues, verify, commit,
+then move to the next system. Between systems, clear reviewer agent
+contexts (shutdown + respawn, or user-initiated context clear) to prevent
+accumulated review data from prior systems causing bleed or context
+pressure in the next review cycle.
+
 ## Work Order
 
 Process by corridor, hop-order within each corridor (closest to Gateway first).
@@ -27,7 +39,7 @@ All tracks run in series on the `copy` branch (parallel worktree approach supers
 |-------|-------|----------|---------|-----------|--------|
 | A | #739 | North Reach | 43 | 4-12 | done |
 | B | #740 | South Reach | 47 | 4-10 | done |
-| C | #741 | East Reach | 47 | 4-10 | hop 4 done (6/47) |
+| C | #741 | East Reach | 47 | 4-9 | done |
 | D | #742 | West Reach | 48 | 4-11 | |
 | E | #743 | Deep Frontier | 73 | 5-12 | |