fix: add data source integrity rule to delegation contract

Workers MUST use provided input data, not fetch external sources.
Adds: Data Source Integrity section, dispatch guidance example,
anti-pattern entry. Root cause of e2e test discrepancies where
writer worker queried Proxmox API instead of using raw data.

mumuni-delegation-prose-contract.prose.md

@@ -66,6 +66,26 @@ Delegation is **mandatory** when any of these apply:
 `curl`, `hermes tools list` — these are decision-making tools. The manager
 reads them directly.
 
+## Data Source Integrity (CRITICAL)
+
+**Workers MUST use the data provided in their task context. They MUST NOT
+fetch their own data from external sources unless explicitly told to.**
+
+When a task says "Read file X and format it", the worker reads file X. It does
+not query a separate API, run its own diagnostics, or pull data from a different
+system. This is the #1 source of cross-worker inconsistency: one worker gathers
+SSH data, another queries the Proxmox API, and the report merges two incompatible
+datasets.
+
+**Rule:** If a worker needs additional data beyond what's in its task description,
+it asks the manager (via relay) — it doesn't go find it on its own.
+
+**This is a hard rule, not a recommendation.** Violating it produces the exact
+type of discrepancy the kanban pipeline exists to prevent: a review worker finds
+"5 nodes present" in the raw data but "5/5 online" in the report — even though
+one of those nodes was unreachable. The report lied because it used data the
+raw data never provided.
+
 ## Worker Selection Matrix
 
 | Worker | Model | Toolsets | Role | Use When |
@@ -100,6 +120,19 @@ dispatch sequentially.
 
 Fire workers via `delegate_task`:
 
+**Critical: Pass the data, not just the goal.** When dispatching a worker that
+processes output from another worker, include the file path AND explicit
+instructions to use ONLY that source. Example:
+
+```
+delegate_task(
+    goal="Format the cluster check into a clean report",
+    context="Source data is at /tmp/proxmox-check-raw.md. Format ONLY the data
+    in that file. Do NOT query the Proxmox API or any other data source. Use the
+    file as your sole source of truth."
+)
+```
+
 **Parallel (independent lanes):**
 ```
 delegate_task(
@@ -203,6 +236,7 @@ Only verified results reach Kwame. Format per channel:
 - ❌ Skipping verification → raw worker output never reaches the user
 - ❌ Delegating single tool calls → keep quick reads/writes at manager level
 - ❌ Firing more than 3 workers in parallel → hard limit
+- ❌ **Workers fetching their own data sources** → a writer worker that queries the Proxmox API when told to "format the raw file" is fabricating data. Use the input given, not external sources
 
 ## Emergency Exception