README: add test harness instructions

README.md

@@ -156,6 +156,51 @@ dsv4/
 
 ---
 
+## Test Harness
+
+Scripts in `tests/` for running tests on the B200 (`root@45.76.247.107`):
+
+### `run_test.sh` — Run a test in a screen session
+
+```bash
+# On the B200:
+cd /root/dsv4-nvfp4-workspace/kernel
+bash tests/run_test.sh tests/unit/test_fmha_v3.py
+```
+
+What it does:
+1. Kills any existing `kernel-test` screen and **SIGKILLs all child processes** (handles deadlocked GPU procs that ignore SIGHUP)
+2. Deletes the old log file
+3. Starts a new `screen -dmS kernel-test` running the test
+4. Logs output to `/tmp/kernel-test.log`
+5. Verifies the screen started
+
+### `check_log.sh` — Check test progress
+
+```bash
+bash tests/check_log.sh
+```
+
+Shows the log contents and whether the screen is still running.
+
+### Local → B200 workflow
+
+```bash
+# 1. Edit locally, commit, push
+cd ~/dev/nvfp4-megamoe-kernel
+git add -A && git commit -m "my change" && git push
+
+# 2. SSH to B200, pull, run
+ssh root@45.76.247.107
+cd /root/dsv4-nvfp4-workspace/kernel && git pull
+bash tests/run_test.sh tests/unit/test_fmha_v3_stage_c_full.py
+
+# 3. Check results
+bash tests/check_log.sh
+```
+
+---
+
 ## Stage C: Online Softmax — SINGLE-TILE ONLY
 
 ### What We Have