Add reusable inventory sweep tooling

.skills/mcc-integration-testing/SKILL.md

@@ -115,6 +115,43 @@ Use this for TPS, movement-cadence, or packet-cadence work:
 
 Run them against a real server with a temp config and summarize counts from the captured logs.
 
+### 4. Full inventory regression sweep
+
+Use this when touching inventory snapshots, player/container slot sync, creative inventory, item-slot serialization, packet palettes, game-mode updates, or block-use paths that open containers:
+
+```bash
+tools/run-inventory-full-sweep.sh --versions "1.21.10 1.21.11"
+```
+
+Default coverage includes:
+
+- player inventory listing and inventory discovery
+- creative give/delete
+- inventory search
+- player right/left click stack split and merge
+- player drop one and drop all
+- chest open via `useblock`
+- container listing and close
+- mirrored player slots in container windows
+- shift-click and shift-right-click transfer
+- container right/left click, cursor stack, drop one, and drop all
+- creative middle-click command path
+- log scan for packet parse failures, queue-empty crashes, unhandled exceptions, and disconnects
+
+Run the Issue #3112 repro after a passing sweep:
+
+```bash
+tools/run-inventory-full-sweep.sh --versions "1.20.4" --run-issue-script
+```
+
+The script writes `summary.tsv` under `RUN_ROOT` and per-version logs under `/tmp/mcc-debug/inventory-full-<version>/mcc-debug.log`.
+
+When a matrix has existing PASS rows, do not rerun them unless a later code change affects that row or the user asks for a full rerun. Derive remaining rows from summaries:
+
+```bash
+awk 'FNR>1 && $2=="PASS" {print $1}' /tmp/mcc-inventory-full-sweep/*/summary.tsv | sort -V | uniq
+```
+
 ## Preconditions
 
 Before running any scenario:
@@ -165,6 +202,8 @@ Optionally override the login name with the fourth argument to the config helper
   - summarize the latest full-spectrum run
 - `tools/run-creative-e2e.sh`
   - ordered creative-mode E2E regression scenario
+- `tools/run-inventory-full-sweep.sh`
+  - full inventory command/API sweep across one or more versions, with optional Issue #3112 MCCScript repro
 
 ## Evidence Discipline
 
@@ -224,3 +263,7 @@ Always summarize:
 - If a test assertion fails, inspect the real MCC output before changing the code or weakening the assertion.
 - If an older server behaves oddly on Linux, check `use-native-transport=false` in `server.properties`.
 - If a matrix row fails before producing `mcc.log` or a command transcript, treat it as a harness failure, fix the environment, and rerun that row before drawing product conclusions.
+- If creative inventory commands report "You must be in Creative gamemode" after RCON switched the player, inspect game-mode update parsing before assuming creative inventory is broken. Modern servers can update local game mode through game event reason `3`.
+- If an inventory row crashes with `Queue empty` or `Failed to process incoming packet`, inspect packet palette routing before changing inventory code. A single shifted packet ID can make a healthy inventory feature look broken.
+- For chest-open failures, separate product and harness causes. The player may be standing inside the chest or suffocating on older servers. Stand beside the chest, put a floor under the player, and retry `useblock`.
+- For shared local servers, a `Done` log line does not prove RCON is ready. Retry setup commands and verify the actual RCON port from `server.properties`.

.skills/mcc-version-adaptation/SKILL.md

@@ -157,6 +157,50 @@ When packet changes are detected:
 2. Create new `PacketPaletteXXX.cs` based on the previous one, adjusting IDs
 3. Update `PacketType18Handler.cs` routing
 
+Use scriptable comparisons instead of eyeballing long packet tables. The packet ID is the registration index in `GameProtocols.java`:
+
+```bash
+python3 - <<'PY'
+import re
+for ver in ["1.21.10", "1.21.11", "26.1"]:
+    path=f"MinecraftOfficial/{ver}-decompiled/net/minecraft/network/protocol/game/GameProtocols.java"
+    text=open(path).read()
+    start=text.index("CLIENTBOUND_TEMPLATE")
+    names=[m.group(1) for m in re.finditer(r"\.addPacket\(([^,]+),", text[start:])]
+    print("==", ver, len(names))
+    for i, name in enumerate(names):
+        print(f"0x{i:02X}", name)
+PY
+```
+
+For focused diffs:
+
+```bash
+python3 - <<'PY'
+import re
+def packets(ver, marker):
+    text=open(f"MinecraftOfficial/{ver}-decompiled/net/minecraft/network/protocol/game/GameProtocols.java").read()
+    start=text.index(marker)
+    return [m.group(1) for m in re.finditer(r"\.addPacket\(([^,]+),", text[start:])]
+left, right = "1.21.10", "1.21.11"
+a, b = packets(left, "CLIENTBOUND_TEMPLATE"), packets(right, "CLIENTBOUND_TEMPLATE")
+for i in range(max(len(a), len(b))):
+    x = a[i] if i < len(a) else "<none>"
+    y = b[i] if i < len(b) else "<none>"
+    if x != y:
+        print(f"0x{i:02X}: {left}={x} | {right}={y}")
+PY
+```
+
+Do the same for `SERVERBOUND_TEMPLATE`. Clientbound and serverbound can change independently. Do not inherit a newer palette just because one side looks similar. For example, `1.21.11` used the same play packet order as `1.21.9/1.21.10` for the tested inventory path, while `26.1` had additional shifts.
+
+Known packet lessons:
+
+- `1.9`, `1.9.1`, and `1.9.2` need their own packet palette. They are not safe to route through the later 1.9.x palette.
+- Pure `1.19` serverbound IDs differ from later 1.19.x. Do not put `MessageAcknowledgment` at `0x03`; pure 1.19 has `ChatCommand` at `0x03`, `ChatMessage` at `0x04`, and `ChatPreview` at `0x05`.
+- A wrong packet palette often appears as unrelated inventory failure: creative give/delete disconnects, `Queue empty`, or `Failed to process incoming packet`.
+- Game event reason `3` is `CHANGE_GAME_MODE`. If RCON changed the player to creative but MCC still refuses creative inventory commands, inspect `ChangeGameState` handling.
+
 ## Step 5: Check Variant Encoding Changes
 
 For entity types that use variant serializers (Cat, Wolf, Frog, Painting), check if the codec changed between versions by inspecting:
@@ -186,6 +230,17 @@ Compare key packet codec classes between versions. Known changes:
 
 When in doubt, compare the relevant packet class (e.g. `ClientboundAddEntityPacket.java`) between versions.
 
+## Step 7.1: Check JoinGame and Respawn Formats
+
+JoinGame and Respawn are high-risk because dimension fields changed several times:
+
+- `1.16` and `1.16.1`: dimension type/name handling uses string identifiers in places where later versions do not.
+- `1.16.2` through `1.18.2`: dimension type can be an NBT compound in JoinGame/Respawn.
+- `1.19+`: dimension type commonly moves back to identifiers.
+- `1.20.6+`: registry-driven IDs appear in more fields.
+
+When a version joins but terrain, inventory, or later packets look misaligned, inspect JoinGame/Respawn first. A single wrong dimension-field read leaves unread bytes in the packet and can make the next packet look broken.
+
 ## Step 8: Update Block Collision Shapes (Physics Engine)
 
 MCC's physics engine uses block collision shape data from PrismarineJS `minecraft-data` to perform accurate AABB collision detection (stored in `MinecraftClient/Physics/BlockShapeData.json`, embedded as a resource).