feat: add 'View full command' option to dangerous command approval (#887)

When a dangerous command is detected and the user is prompted for
approval, long commands are truncated (80 chars in fallback, 70 chars
in the TUI). Users had no way to see the full command before deciding.

This adds a 'View full command' option across all approval interfaces:

- CLI fallback (tools/approval.py): [v]iew option in the prompt menu.
  Shows the full command and re-prompts for approval decision.
- CLI TUI (cli.py): 'Show full command' choice in the arrow-key
  selection panel. Expands the command display in-place and removes
  the view option after use.
- CLI callbacks (callbacks.py): 'view' choice added to the list when
  the command exceeds 70 characters.
- Gateway (gateway/run.py): 'full', 'show', 'view' responses reveal
  the complete command while keeping the approval pending.

Includes 7 new tests covering view-then-approve, view-then-deny,
short command fallthrough, and double-view behavior.

Closes community feedback about the 80-char cap on dangerous commands.

tools/approval.py

@@ -184,43 +184,52 @@ def prompt_dangerous_approval(command: str, description: str,
 
     os.environ["HERMES_SPINNER_PAUSE"] = "1"
     try:
-        print()
-        print(f"  ⚠️  DANGEROUS COMMAND: {description}")
-        print(f"      {command[:80]}{'...' if len(command) > 80 else ''}")
-        print()
-        print(f"      [o]nce  |  [s]ession  |  [a]lways  |  [d]eny")
-        print()
-        sys.stdout.flush()
+        is_truncated = len(command) > 80
+        while True:
+            print()
+            print(f"  ⚠️  DANGEROUS COMMAND: {description}")
+            print(f"      {command[:80]}{'...' if is_truncated else ''}")
+            print()
+            view_hint = "  |  [v]iew full" if is_truncated else ""
+            print(f"      [o]nce  |  [s]ession  |  [a]lways  |  [d]eny{view_hint}")
+            print()
+            sys.stdout.flush()
 
-        result = {"choice": ""}
+            result = {"choice": ""}
 
-        def get_input():
-            try:
-                result["choice"] = input("      Choice [o/s/a/D]: ").strip().lower()
-            except (EOFError, OSError):
-                result["choice"] = ""
+            def get_input():
+                try:
+                    result["choice"] = input("      Choice [o/s/a/D]: ").strip().lower()
+                except (EOFError, OSError):
+                    result["choice"] = ""
 
-        thread = threading.Thread(target=get_input, daemon=True)
-        thread.start()
-        thread.join(timeout=timeout_seconds)
+            thread = threading.Thread(target=get_input, daemon=True)
+            thread.start()
+            thread.join(timeout=timeout_seconds)
 
-        if thread.is_alive():
-            print("\n      ⏱ Timeout - denying command")
-            return "deny"
+            if thread.is_alive():
+                print("\n      ⏱ Timeout - denying command")
+                return "deny"
 
-        choice = result["choice"]
-        if choice in ('o', 'once'):
-            print("      ✓ Allowed once")
-            return "once"
-        elif choice in ('s', 'session'):
-            print("      ✓ Allowed for this session")
-            return "session"
-        elif choice in ('a', 'always'):
-            print("      ✓ Added to permanent allowlist")
-            return "always"
-        else:
-            print("      ✗ Denied")
-            return "deny"
+            choice = result["choice"]
+            if choice in ('v', 'view') and is_truncated:
+                print()
+                print("      Full command:")
+                print(f"      {command}")
+                is_truncated = False  # show full on next loop iteration too
+                continue
+            if choice in ('o', 'once'):
+                print("      ✓ Allowed once")
+                return "once"
+            elif choice in ('s', 'session'):
+                print("      ✓ Allowed for this session")
+                return "session"
+            elif choice in ('a', 'always'):
+                print("      ✓ Added to permanent allowlist")
+                return "always"
+            else:
+                print("      ✗ Denied")
+                return "deny"
 
     except (EOFError, KeyboardInterrupt):
         print("\n      ✗ Cancelled")