chore: baseline snapshot — prior-session work + ha-consistency-invariants spec family

Pre-existing uncommitted work: ha-repl-hardening payload data plane (7.x),
heartbeat liveness fix (Req 1.3), connection-reuse ASAN fixes, doc cleanup.
New: ha-consistency-invariants umbrella (requirements/design/research) and
its four implementation sub-specs (specs generated via batch, cross-spec
review applied), steering roadmap + product.md Raft+CP decision.

src/docs/xce.md

@@ -1,32 +1,58 @@
 Help of XCE
 ===========
 
-This is the entrypoint of xce tool. Currently, we have following sub-commands available:
+This is the entrypoint of xce tool. Currently, we have following sub-commands
+available:
 
-- controller
-- worker
-- scheduler
-- apiserver
-- shell
+- **controller** — start xce controller daemon
+- **worker** — start xcecd worker daemon
+- **scheduler** — start xce scheduler daemon
+- **apiserver** — start xce REST API server
+- **shell** — interactive bash shell for troubleshooting
+- **xcecli** — CLI tool for cluster interaction (job submit, query, admin)
 
-If you run xce without any parameter or with parameter which is not in above, then it will show this help screen
+If you run xce without any parameter or with a parameter not listed above, it
+will show this help screen.
 
 ## controller
 
-This command with start xce controller with given parameters after  controller  sub-command
+Start the xce controller daemon with the given parameters after the
+`controller` sub-command.
+
+Example:
+```
+xce controller --config /etc/xce/controller.yaml
+```
 
 ## scheduler
 
-This command with start xce scheduler with given parameters after  scheduler  sub-command
+Start the xce scheduler daemon with the given parameters after the
+`scheduler` sub-command.
 
 ## worker
 
-This command will start xcecd with given parameters after worker sub-command
+Start xcecd with the given parameters after the `worker` sub-command.
 
 ## apiserver
 
-This command will start xce apiserver with given parameters after apiserver sub-command
+Start the xce REST API server with the given parameters after the
+`apiserver` sub-command. The API server provides HTTP endpoints for job
+submission, queue management, and cluster queries, backed by JWT
+authentication and RBAC authorization.
+
+## xcecli
+
+The xce CLI (`src/frontend/xcecli/`) provides command-line access to the
+cluster. Common operations:
+
+- `xcecli job submit <jobspec>` — submit a job
+- `xcecli job list` — list jobs
+- `xcecli queue status` — show queue state
+
+Built as a standalone Go binary; communicates with the API server over
+its REST interface.
 
 ## shell
 
-An interactive bash shell to start, this is just for trouble shoot
+An interactive bash shell used for troubleshooting and inspection. Not
+intended for normal cluster operation.