chore: consolidate follow-up tasks from Round 72

- Remove duplicate TASK-197 (seq fix) - covered by TASK-199
- Renumber TASK-197 (performance) to TASK-201
- Create TASK-202 (P0 CRITICAL): INSERT INTO crsql_changes failure

Task summary:
- TASK-199 (MEDIUM): seq value divergence (Zig=1, Rust=0)
- TASK-200 (LOW): Zig validation gaps (more permissive than Rust)
- TASK-201 (LOW): Performance regression parity tests
- TASK-202 (P0 CRITICAL): Fix INSERT INTO crsql_changes failure

Author: subtleGradient

.tasks/triage/TASK-197-fix-seq-off-by-one.md

@@ -1,4 +1,4 @@
-# TASK-197 — Performance Regression Parity Tests
+# TASK-201 — Performance Regression Parity Tests
 
 ## Goal
 Identify performance divergences that might indicate algorithmic differences.

…ASK-197-performance-regression-parity.md …ASK-201-performance-regression-parity.md.tasks/triage/TASK-197-performance-regression-parity.md renamed to .tasks/triage/TASK-201-performance-regression-parity.md .tasks/triage/TASK-197-performance-regression-parity.md renamed to .tasks/triage/TASK-201-performance-regression-parity.md

@@ -0,0 +1,84 @@
+# TASK-202 — Fix INSERT INTO crsql_changes Failure (CRITICAL)
+
+## Goal
+Fix the critical bug where `INSERT INTO crsql_changes` fails in the Zig implementation, completely breaking cross-device sync.
+
+## Status
+- State: triage
+- Priority: **P0 CRITICAL** (sync is completely broken)
+- Discovered: 2025-12-25 (TASK-194 real-world app simulation)
+
+## Problem
+
+When applying changes from another device via `INSERT INTO crsql_changes`, the Zig implementation fails:
+
+```
+debug(changes_vtab): changesUpdate INSERT: table=todos, cid=title...
+debug(changes_vtab): changesUpdate: no local row, inserting new row
+debug(changes_vtab): changesUpdate: insertOrUpdateColumn failed
+Error: stepping, SQL logic error
+```
+
+**This is the core sync mechanism of cr-sqlite. Without it, the extension is non-functional.**
+
+## Reproduction
+
+```bash
+cd /Users/tom/Developer/effect-native/cr-sqlite
+bash zig/harness/test-app-todo.sh
+```
+
+The test creates a todo on "Device A", exports changes via `SELECT * FROM crsql_changes`, then tries to apply them to "Device B" via `INSERT INTO crsql_changes`. Rust/C succeeds, Zig fails.
+
+Minimal reproduction:
+```sql
+-- Device A (Zig)
+CREATE TABLE todos(id TEXT PRIMARY KEY, title TEXT);
+SELECT crsql_as_crr('todos');
+INSERT INTO todos VALUES ('1', 'Test');
+
+-- Export changes
+SELECT * FROM crsql_changes;
+-- Returns: todos|1|title|Test|1|1|<site_id>|1|1
+
+-- Device B (Zig) - THIS FAILS
+CREATE TABLE todos(id TEXT PRIMARY KEY, title TEXT);
+SELECT crsql_as_crr('todos');
+INSERT INTO crsql_changes VALUES ('todos', '1', 'title', 'Test', 1, 1, X'...', 1, 1);
+-- Error: SQL logic error
+```
+
+## Root Cause (Suspected)
+
+The error occurs in `zig/src/changes_vtab.zig` in the `changesUpdate` function, specifically in the `insertOrUpdateColumn` code path when the local row doesn't exist.
+
+Possible causes:
+1. SQL statement preparation failure (wrong column names/types)
+2. Missing table/column in PKS table lookup
+3. Incorrect binding of site_id blob
+4. Schema mismatch between clock table and expected format
+
+## Files to Investigate
+
+- `zig/src/changes_vtab.zig` — `changesUpdate` function, especially "no local row" branch
+- `zig/src/merge_insert.zig` — `insertOrUpdateColumn` and related functions
+- `zig/harness/test-app-todo.sh` — Reproduction script
+
+## Acceptance Criteria
+
+1. [ ] `INSERT INTO crsql_changes` succeeds for new rows
+2. [ ] `bash zig/harness/test-app-todo.sh` passes on Zig
+3. [ ] All 3 app simulation tests pass (todo, chat, inventory)
+4. [ ] Existing parity tests continue to pass
+
+## Parent Docs / Cross-links
+
+- Discovered in: `.tasks/active/TASK-194-real-world-app-simulation.md`
+- Test scripts: `zig/harness/test-app-*.sh`
+- Gap backlog: `research/zig-cr/92-gap-backlog.md`
+
+## Progress Log
+- 2025-12-25: Created from TASK-194 findings. This is P0 blocker.
+
+## Completion Notes
+(Empty until done.)