fix: correct NEW_FMT_VER for v2 case and document stateless field in README

Author: dantengsky

tests/compat_fuse/README.md

@@ -9,12 +9,13 @@ Tests write-then-read compatibility of fuse-table format across databend-query v
 
 All test cases are defined in `test_cases.yaml`. Each entry specifies:
 
-| Field    | Description                                                        |
-|----------|--------------------------------------------------------------------|
-| `writer` | Query version that writes data (`"current"` = latest build)       |
-| `reader` | Query version that reads data (`"current"` = latest build)        |
-| `meta`   | Meta-service versions to run in order (upgrades on-disk meta data) |
-| `suite`  | sqllogictest sub-directory under `compat-logictest/`               |
+| Field      | Description                                                        |
+|------------|--------------------------------------------------------------------|
+| `writer`   | Query version that writes data (`"current"` = latest build)       |
+| `reader`   | Query version that reads data (`"current"` = latest build)        |
+| `meta`     | Meta-service versions to run in order (upgrades on-disk meta data) |
+| `suite`    | sqllogictest sub-directory under `compat-logictest/`               |
+| `stateless`| *(optional)* Shell script to run after the read phase (e.g. flashback/compaction tests) |
 
 To add a test case, append an entry to `test_cases.yaml`.
 
@@ -59,6 +60,7 @@ For each case, the script runs three phases:
 1. **Write** — start meta (first version) + query (writer version), run `fuse_compat_write`
 2. **Meta upgrade** — cycle through all meta versions to upgrade on-disk data
 3. **Read** — start meta (last version) + query (reader version), run `fuse_compat_read`
+4. **Stateless** *(optional)* — run shell script from `compat-stateless/` if `stateless` field is set
 
 ## Testing data
 

tests/compat_fuse/test_cases.yaml

@@ -17,7 +17,7 @@
 - { writer: "1.2.680", reader: current, meta: [1.2.680, 1.2.833], suite: udf }
 
 # --- Meta compression compat (with stateless flashback/compaction tests) ---
-- { writer: "1.0.56", reader: current, meta: [1.0.56, 1.2.527, 1.2.677, 1.2.833], suite: 01_meta_compression, stateless: "across_versions.sh 2 3" }
+- { writer: "1.0.56", reader: current, meta: [1.0.56, 1.2.527, 1.2.677, 1.2.833], suite: 01_meta_compression, stateless: "across_versions.sh 2 4" }
 - { writer: "1.1.30", reader: current, meta: [1.1.30, 1.2.527, 1.2.677, 1.2.833], suite: 02_meta_compression_v3_to_v4, stateless: "across_versions.sh 3 4" }
 
 # --- Forward compat: current writer -> old reader ---