diff --git a/strix/interface/cli.py b/strix/interface/cli.py
index a8992ce4..482e625a 100644
--- a/strix/interface/cli.py
+++ b/strix/interface/cli.py
@@ -97,7 +97,9 @@ async def run_cli(args: Any) -> None:  # noqa: PLR0915
         "workspace_files": getattr(args, "workspace_files", None) or [],
         "scope_mode": getattr(args, "scope_mode", "auto"),
         "diff_base": getattr(args, "diff_base", None),
-        "resume_instruction": getattr(args, "user_explicit_instruction", None) or "",
+        "resume_instruction": getattr(args, "resume_instruction", None)
+        or getattr(args, "user_explicit_instruction", None)
+        or "",
     }
 
     report_state = ReportState(args.run_name)
diff --git a/strix/interface/cli_args.py b/strix/interface/cli_args.py
index f27dfe4e..b21230de 100644
--- a/strix/interface/cli_args.py
+++ b/strix/interface/cli_args.py
@@ -24,6 +24,15 @@ from strix.report.runs import list_run_summaries
 # Severities ``--fail-on`` accepts, most severe first.
 FAIL_ON_SEVERITIES = ("critical", "high", "medium", "low", "info")
 
+# Injected into a resumed session that was widened past its recorded diff
+# scope, so the diff-scope preamble replayed from the original conversation
+# stops telling the agents to report findings only inside the old diff.
+RESUME_SCOPE_WIDENED_INSTRUCTION = (
+    "The diff scope of the original run has been lifted (--scope-mode full): "
+    "analyze the full repository. Findings are no longer limited to the "
+    "changes listed in the earlier scope instructions."
+)
+
 
 def get_version() -> str:
     try:
@@ -548,14 +557,24 @@ def load_resume_state(args: argparse.Namespace) -> None:
         args.scope_mode = persisted_scope_mode
     if state.get("diff_base") and not args.diff_base:
         args.diff_base = state.get("diff_base")
+    # What reaches the resumed session as a fresh message: the runner injects
+    # scan_config["resume_instruction"], because a replayed session would
+    # otherwise ignore any new instruction entirely.
+    args.resume_instruction = args.user_explicit_instruction or ""
     if args.scope_mode == "full":
         # An explicit --scope-mode full widens the resume to the full
         # repository, as --help promises; the flag's "auto" default keeps the
-        # intent unambiguous. The persisted instruction carries the diff-scope
-        # preamble, so a widened resume rebuilds it from the clean user text.
+        # intent unambiguous.
+        widened = bool(isinstance(args.diff_scope, dict) and args.diff_scope.get("active"))
         args.diff_scope = {"active": False, "mode": "full"}
-        if not args.user_explicit_instruction and args.user_instruction:
-            args.instruction = args.user_instruction
+        if widened and not args.user_explicit_instruction:
+            # The instruction recorded for a diff-scoped run carries the
+            # preamble prepare_run() prepended to it; the widened resume
+            # records the clean user text instead, and injects a note into
+            # the replayed session so the old restriction is lifted for
+            # the agents too, not just in the published record.
+            args.instruction = state.get("user_instruction") or None
+            args.resume_instruction = RESUME_SCOPE_WIDENED_INSTRUCTION
     agents_path = runtime_state_dir(run_dir) / "agents.json"
     if not agents_path.exists():
         raise ResumeError(
diff --git a/strix/interface/tui/runtime.py b/strix/interface/tui/runtime.py
index ae983236..88ab8198 100644
--- a/strix/interface/tui/runtime.py
+++ b/strix/interface/tui/runtime.py
@@ -99,7 +99,9 @@ class GoTuiRuntime:
             "workspace_files": getattr(self.args, "workspace_files", None) or [],
             "scope_mode": self.args.scope_mode,
             "diff_base": self.args.diff_base,
-            "resume_instruction": self.args.user_explicit_instruction or "",
+            "resume_instruction": getattr(self.args, "resume_instruction", None)
+            or getattr(self.args, "user_explicit_instruction", None)
+            or "",
             "workspace_mount": getattr(self.args, "workspace_mount", None) or "",
             "workspace_subdir": getattr(self.args, "workspace_subdir", None) or "",
         }
diff --git a/tests/test_resume_scope.py b/tests/test_resume_scope.py
index 6d8f11bc..91321c4f 100644
--- a/tests/test_resume_scope.py
+++ b/tests/test_resume_scope.py
@@ -10,6 +10,8 @@ from typing import TYPE_CHECKING, Any
 
 import pytest
 
+from strix.interface.cli_args import RESUME_SCOPE_WIDENED_INSTRUCTION
+
 
 if TYPE_CHECKING:
     from pathlib import Path
@@ -78,6 +80,7 @@ def test_resume_restores_persisted_scope_over_flag_defaults(
     assert args.diff_base == "origin/main"
     assert args.diff_scope == {"active": True, "mode": "diff", "repos": []}
     assert args.instruction == PREAMBLE + "find auth bugs"
+    assert args.resume_instruction == ""
 
 
 def test_resume_honors_scope_mode_full(tmp_path: Path, monkeypatch: pytest.MonkeyPatch) -> None:
@@ -96,8 +99,10 @@ def test_resume_honors_scope_mode_full(tmp_path: Path, monkeypatch: pytest.Monke
     assert args.scope_mode == "full"
     assert args.diff_scope == {"active": False, "mode": "full"}
     # The recorded instruction carries the diff-scope preamble; the widened
-    # resume keeps only the clean user text.
+    # resume keeps only the clean user text, and injects a note lifting the
+    # old restriction into the replayed session.
     assert args.instruction == "find auth bugs"
+    assert args.resume_instruction == RESUME_SCOPE_WIDENED_INSTRUCTION
 
 
 def test_resume_honors_scope_mode_full_with_new_instruction(
@@ -118,12 +123,13 @@ def test_resume_honors_scope_mode_full_with_new_instruction(
     assert args.scope_mode == "full"
     assert args.diff_scope == {"active": False, "mode": "full"}
     assert args.instruction == "check the API"
+    assert args.resume_instruction == "check the API"
 
 
 def test_resume_honors_scope_mode_full_without_recorded_user_instruction(
     tmp_path: Path, monkeypatch: pytest.MonkeyPatch
 ) -> None:
-    """Widening still takes effect when the run predates user_instruction."""
+    """A widened resume drops a preamble-only instruction and injects the note."""
     work = tmp_path / "project"
     work.mkdir()
     monkeypatch.chdir(tmp_path)
@@ -136,7 +142,38 @@ def test_resume_honors_scope_mode_full_without_recorded_user_instruction(
     args = _resume(monkeypatch, "--scope-mode", "full")
 
     assert args.diff_scope == {"active": False, "mode": "full"}
-    assert args.instruction == PREAMBLE
+    assert args.instruction is None
+    assert args.resume_instruction == RESUME_SCOPE_WIDENED_INSTRUCTION
+
+
+def test_resume_with_scope_mode_full_on_a_full_run_injects_nothing(
+    tmp_path: Path, monkeypatch: pytest.MonkeyPatch
+) -> None:
+    """Re-asserting full on a run that was already full is a plain no-op."""
+    work = tmp_path / "project"
+    work.mkdir()
+    monkeypatch.chdir(tmp_path)
+    _write_run_record(
+        tmp_path / "strix_runs",
+        "pentest_abcd",
+        {
+            "run_name": "pentest_abcd",
+            "targets_info": [],
+            "local_sources": [],
+            "instruction": "find auth bugs",
+            "user_instruction": "find auth bugs",
+            "scan_mode": "deep",
+            "scope_mode": "full",
+            "diff_scope": {"active": False, "mode": "full"},
+            "workspace_mount": str(work),
+        },
+    )
+
+    args = _resume(monkeypatch, "--scope-mode", "full")
+
+    assert args.diff_scope == {"active": False, "mode": "full"}
+    assert args.instruction == "find auth bugs"
+    assert args.resume_instruction == ""
 
 
 @pytest.mark.parametrize("extra", [["--scope-mode", "diff"], ["--diff-base", "origin/main"]])