gpuq data contract: declarative per-job in/out sync (pull inputs, push outputs every 120s + at exit), gpuq_sync.sh helper

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

scripts/GPUQ.md

@@ -25,6 +25,33 @@ happens in the filename (`00_`, `01_`, …). The bucket is both transport
 and durable state: a dead node's pending jobs stay visible and can be
 moved to another worker with one `rclone move`.
 
+## Data contract (selective sync)
+
+Jobs declare what they need and what they produce as comments; the worker
+does the rest — no node needs everything, and results survive node death:
+
+```
+# gpuq-in:  results-loop/mbpp_data.json results-loop/adapter_code.pt
+# gpuq-out: results-loop/eval_code_gate*.json results/jbar_31b.pt
+```
+
+Paths are repo-relative, mirrored at `jspace:jspace/<same path>`.
+Inputs are pulled before the job starts. Outputs are pushed every
+`$GPUQ_SYNC_EVERY` seconds (default 120) while the job runs and once at
+exit — a dying node loses at most one interval. The in-flight log is
+also mirrored to `gpuq/<worker>/running/` each cycle. Globs allowed in
+basenames; repeat lines for more paths; jobs with no declarations sync
+nothing (backward compatible). Manual counterpart from any machine:
+
+```
+scripts/gpuq_sync.sh pull results-loop "eval_code_gate*.json"
+scripts/gpuq_sync.sh push results-loop "adapter_code.pt"
+```
+
+Nodes need the rclone remote configured for any of this; keep a scoped
+(write-limited) key for rented nodes. Without credentials the worker
+still runs jobs — sync lines just no-op.
+
 ## Bucket layout
 
 ```