test: add bats test suite for lib/ helper scripts

110 tests across 10 test files covering all lib/ scripts:
- archeflow-event.sh: JSONL format, seq numbering, parent fields, validation
- archeflow-memory.sh: add/list/decay/forget/inject/extract commands
- archeflow-git.sh: branch creation, commit format, merge strategies, safety
- archeflow-report.sh: markdown output, summary mode, in-progress handling
- archeflow-progress.sh: progress.md generation, JSON mode, error handling
- archeflow-score.sh: archetype scoring, effectiveness report, validation
- archeflow-dag.sh: DAG rendering, color flags, tree structure
- archeflow-rollback.sh: arg parsing, phase validation, mutual exclusivity
- archeflow-init.sh: template listing, clone from project, arg validation
- archeflow-review.sh: diff modes, stats, branch/commit range review

Includes test_helper.bash (shared setup/teardown with temp git repos)
and scripts/run-tests.sh runner.

tests/archeflow-rollback.bats

@@ -0,0 +1,58 @@
+# Tests for archeflow-rollback.sh — post-merge test and phase rollback.
+#
+# Validates: argument parsing, mutual exclusivity, phase validation, test-cmd config reading.
+
+setup() {
+  load test_helper
+  _common_setup
+}
+
+teardown() {
+  _common_teardown
+}
+
+@test "rollback: exits with error when called with no args" {
+  run "$LIB_DIR/archeflow-rollback.sh"
+  [ "$status" -ne 0 ]
+}
+
+@test "rollback: rejects mutually exclusive --to and --test-cmd" {
+  run "$LIB_DIR/archeflow-rollback.sh" test-run --to plan --test-cmd "true"
+  [ "$status" -eq 2 ]
+  [[ "$output" == *"mutually exclusive"* ]]
+}
+
+@test "rollback: rejects invalid phase names" {
+  run "$LIB_DIR/archeflow-rollback.sh" test-run --to invalid-phase
+  [ "$status" -eq 2 ]
+  [[ "$output" == *"Invalid phase"* ]]
+}
+
+@test "rollback: accepts valid phase names (plan, do, check)" {
+  # This will fail because no git branch exists, but should NOT fail on phase validation
+  run "$LIB_DIR/archeflow-rollback.sh" test-run --to plan
+  # Should fail later (archeflow-git.sh rollback) not on phase validation
+  [[ "$output" != *"Invalid phase"* ]]
+}
+
+@test "rollback: exits 2 when no test command available" {
+  run "$LIB_DIR/archeflow-rollback.sh" test-run
+  [ "$status" -eq 2 ]
+  [[ "$output" == *"No test command"* ]]
+}
+
+@test "rollback: reads test_command from config.yaml" {
+  mkdir -p .archeflow
+  echo 'test_command: "echo ok"' > .archeflow/config.yaml
+  # HEAD won't have archeflow in its message, but the script just warns and proceeds
+  run "$LIB_DIR/archeflow-rollback.sh" test-run
+  # It should pick up the command and try to run it (test should pass -> exit 0)
+  [ "$status" -eq 0 ]
+  [[ "$output" == *"Tests passed"* ]]
+}
+
+@test "rollback: rejects unknown options" {
+  run "$LIB_DIR/archeflow-rollback.sh" test-run --unknown-flag
+  [ "$status" -eq 2 ]
+  [[ "$output" == *"Unknown option"* ]]
+}