feat: add safe cap call output modes

docs/current_roadmap.md

@@ -43,8 +43,8 @@ clear operator feedback before adding more architecture.
 - Completed: bounded RPC CLI smoke runbook with cleanup commands:
   [`RPC CLI smoke runbook`](runbooks/rpc-cli-smoke.md).
 - Next docs/ergonomics cleanup: make `cap call` output safer for humans without
-  changing default JSON semantics. Active plan:
-  [`cap call output safety`](superpowers/plans/2026-06-09-cap-call-output-safety.md).
+  changing default JSON semantics. Implementation:
+  [`cap call output safety`](historical/superpowers/plans/2026-06-09-cap-call-output-safety.md).
 - Future smoke automation: turn the manual RPC CLI smoke runbook into a small
   script once the command sequence stabilizes.
 - Keep status read-only; do not mutate registry, auth, config, or stores.

docs/runbooks/rpc-cli-smoke.md

@@ -80,6 +80,14 @@ Expected:
 - `outcome` is `ok`.
 - Output is small and machine-readable.
 
+Optionally, test compact output:
+
+```bash
+uv run wf --config wf.config.json cap call wf.std.constant --input '{"value":"smoke"}' --format compact
+```
+
+Expected: one bounded line with `outcome=ok`.
+
 Avoid using arbitrary MCP tools here unless their output shape is known. MCP
 content-block envelopes can be large and should not be treated like compact
 workflow output.

docs/wf_cli.md

@@ -175,6 +175,24 @@ wf cap call wf.std.constant --input '{"value": "hello"}'
 wf --url http://127.0.0.1:8765/rpc cap call everything.default.echo --input '{"message": "hello"}'
 ```
 
+Use `--format compact` for a bounded one-line summary that avoids dumping large
+MCP content-block envelopes:
+
+```bash
+wf cap call wf.std.constant --input '{"value": "hello"}' --format compact
+```
+
+Use `--format text --unwrap-text` to extract exactly one MCP text content block.
+This mode refuses images, resources, blobs, multiple content blocks, and
+non-MCP output:
+
+```bash
+wf cap call everything.default.echo --input '{"message": "hello"}' --format text --unwrap-text
+```
+
+Use `--max-output-chars N` to bound compact/text terminal output. JSON output
+is never truncated.
+
 `cap call` is an authoring/runtime smoke test. It uses the same local or remote
 target selection as the rest of the CLI and returns a normalized outcome,
 output, source id, and diagnostics. Use it to confirm payload shape and upstream