docs: hint at jq file injection for safe-output body fields

actions/setup/md/mcp_cli_tools_prompt.md

@@ -13,6 +13,15 @@ printf '{"item_number":42,"body":"### Title\n\nBody."}' | safeoutputs add_commen
 # or write to a file: safeoutputs create_pull_request . < /tmp/payload.json
 ```
 
+To inject an entire local file as the `body` field without re-embedding its content in the model context, use `jq -Rs`:
+```bash
+jq -Rs --arg discussion_number "$DISCUSSION_NUMBER" \
+  '{discussion_number: ($discussion_number|tonumber), body: .}' \
+  discussion-body.md \
+  | safeoutputs update_discussion .
+```
+`jq -Rs` reads the file as a raw string (`-R`) and slurps it into a single JSON string value (`-s`), so `body` is always a valid JSON field. Piping `cat file | safeoutputs ...` does not populate `body` and will be rejected.
+
 The generated command syntax above is schema-derived from each enabled tool's final `inputSchema` and is the source of truth for required/optional parameters.
 Use `<server> --help` and `<server> <tool> --help` for the same schema-derived signatures and examples before calling any command.
 </mcp-clis>

actions/setup/md/safe_outputs_prompt.md

@@ -15,5 +15,5 @@ Safe-output calls are write-once declarations for real downstream side effects.
 
 temporary_id: optional cross-reference field for future resources created by safe outputs. Canonical form: '#aw_' followed by 3–12 alphanumeric or underscore characters — e.g., '#aw_abc1', '#aw_pr_fix'. Pattern: /^#?aw_[A-Za-z0-9_]{3,12}$/i (the '#' prefix is optional; bare 'aw_abc1' is accepted and normalised to '#aw_abc1' automatically). Use this form for all field values (temporary_id, item_number, issue_number, parent, etc.). In body/markdown text, '#aw_abc1' references are replaced with the real issue/PR number after creation. Omit entirely when not needed.
 
-**Note**: safeoutputs tools do NOT support `@filename` file name expansion. Always provide content inline — do not use `@filename` references in tool arguments.
+**Note**: safeoutputs tools do NOT support `@filename` file name expansion. Always provide content inline — do not use `@filename` references in tool arguments. To inject an entire file as the `body` field, use `jq -Rs` to read it as a JSON string and pipe the resulting payload: `jq -Rs '{body: .}' file.md | safeoutputs update_discussion .`
 </safe-outputs>