docs: tagged checkpoints do work on cloud-protected VPGs

The repo said, in four places, that a tagged checkpoint cannot be inserted
when the protected site is Azure or AWS. That came from the 9.0 API
reference. It is wrong on 10.9.10.

Measured against the lab: both an AWS-protected and an Azure-protected VPG
accepted the insert, the Zerto task reached Completed, and the checkpoint
appeared in the journal. This is the second doc claim this repo carried
that live 10.9 contradicts, after the VPG status enum.

What actually differs is latency and granularity, and both are set by the
PROTECTED site, not the recovery site:

  protected at   journal gap   tag visible after
  vSphere        5s            ~4s
  Azure          60s           ~34s
  AWS            630s          ~128s

There is a sharper consequence than slowness. The tagged checkpoint is
stamped about 30s AFTER the insert request, so on a cloud-protected VPG an
agent that mutates promptly puts its change inside the checkpoint that was
supposed to precede it. Recovering from that tag would restore the broken
state. The docs now say to use the newest checkpoint that already existed
when the guard ran.

Two of the four were message text, not prose. wait_for_tag's timeout
message asserted the insert was unsupported when the real cause was its own
45s budget being far too short for a VPG that checkpoints every 630s, so it
told operators the wrong thing at exactly the wrong moment. It now says to
check the Zerto task before concluding the insert failed.

The 45s timeout itself is still wrong for cloud sources and needs to become
cadence-aware. That is a behaviour change, so it is not in this commit.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>
Claude-Session: https://claude.ai/code/session_016yVfC5nvZowoLFnEGWhLGn

README.md

@@ -64,7 +64,22 @@ Git never had the file. RPO is the journal, not last night's backup.
 
 vSphere ZVM 10.x and ZCA on AWS/Azure, same REST paths. HVM is out (separate swagger). Failover Live is not a tool.
 
-Tagged checkpoints cannot be inserted when the **protected** site is Azure or AWS (Zerto API). Point this server at the vSphere protected ZVM.
+Tagged checkpoints **do** work when the protected site is Azure or AWS. The 9.0 API
+reference says they cannot be inserted; that is wrong on 10.9.10, where both were
+accepted and the task reached `Completed`.
+
+What differs is latency and granularity, both set by the **protected** site:
+
+| protected at | journal gap | tag visible after |
+|---|---|---|
+| vSphere | 5s | ~4s |
+| Azure | 60s | ~34s |
+| AWS | 630s | ~128s |
+
+The tagged checkpoint is also stamped about 30s *after* the insert request, so on a
+cloud-protected VPG a prompt mutation can land *inside* the checkpoint meant to
+precede it. Recover from the newest checkpoint that already existed when the guard
+ran, not from the tag.
 
 ## Not this product
 

skills/zerto-rewind/SKILL.md

@@ -70,7 +70,10 @@ so a stuck session blocks the next recovery. Find it with
 ## Facts that bite
 
 - A tagged checkpoint is crash-consistent, not app-quiesced.
-- Tagged checkpoints are not supported when the **protected** site is Azure or AWS. Talk to the vSphere protected ZVM.
+- Tagged checkpoints work on Azure and AWS protected VPGs, but they appear late:
+  ~34s (Azure) and ~128s (AWS) versus ~4s on vSphere, and the checkpoint is stamped
+  about 30s after you ask for it. On those VPGs the tag can end up *after* your
+  change, so treat the newest checkpoint that already existed as the rewind point.
 - 10.9 FLR Operator RBAC fails; Administrator is the documented workaround.
 - FLR cannot run during clone, test, live failover, or EJC.
 - Linux FLR: files >1.5GB are a bad idea; some characters in names are refused.

src/zerto_rewind_mcp/checkpoints.py

@@ -93,7 +93,10 @@ async def wait_for_tag(
     raise ZertoError(
         f"Tagged checkpoint {tag!r} did not appear on VPG {vpg_identifier} "
         f"within {timeout_s:.0f}s. Do not mutate. "
-        "If the protected site is Azure or AWS, tagged checkpoints are not supported."
+        "On a cloud-protected VPG the tag routinely takes longer than this to appear "
+        "(measured ~34s on Azure, ~128s on AWS), so this timeout may simply be too "
+        "short rather than the insert having failed. Check the Zerto task before "
+        "assuming it did not land."
     )
 
 

src/zerto_rewind_mcp/protection.py

@@ -137,8 +137,7 @@ def find_from_rows(query: str, rows: list[dict[str, Any]]) -> FindResult:
             outcome="none",
             query=query,
             message=(
-                f"VM {vm.vm_name} ({vm.vm_identifier}) has no VPG. "
-                "Unprotected: refuse the change."
+                f"VM {vm.vm_name} ({vm.vm_identifier}) has no VPG. Unprotected: refuse the change."
             ),
             vm=vm,
         )

src/zerto_rewind_mcp/server.py

@@ -133,8 +133,9 @@ async def zerto_create_tagged_checkpoint(
     the Zerto API accepts, so this is the only place that context can live.
 
     Name format: ai:<agent> | <action> | vm=<vm> | change=<change_id> | <utc>
-    Docs: tagged checkpoints are not supported when the protected site is Azure or AWS;
-    run this against the vSphere protected ZVM.
+    Works on Azure and AWS protected VPGs despite what the 9.0 API reference says,
+    but the tag appears late there (~34s Azure, ~128s AWS) and is stamped after the
+    request, so it may sit after a prompt mutation.
     """
     try:
         result = await _find(query)

src/zerto_rewind_mcp/status.py

@@ -127,7 +127,6 @@ def can_tag(status: int | None, substatus: int | None) -> tuple[bool, str | None
         return False, f"VPG status is {status_name(status)}; not MeetingSLA"
     if substatus in SYNCING:
         return False, (
-            f"VPG is {substatus_name(substatus)}; "
-            "checkpoints are not durable until sync ends"
+            f"VPG is {substatus_name(substatus)}; checkpoints are not durable until sync ends"
         )
     return True, None