diff --git a/templates/commands/converge.md b/templates/commands/converge.md
index eadb96ee58..30a1eca241 100644
--- a/templates/commands/converge.md
+++ b/templates/commands/converge.md
@@ -201,6 +201,23 @@ Append to the **end** of `tasks.md`, per the append contract:
 
 1. Scan all existing task IDs; let `M` be the maximum. Determine the next phase number `N`
    (highest existing phase + 1).
+
+   **Drop findings that existing unchecked tasks already cover.** Compare each actionable
+   finding against every `- [ ]` task already in `tasks.md` — outside code fences, the same
+   rule `__SPECKIT_COMMAND_CLARIFY__` applies — matching on the work described and the file
+   paths or `<source-ref>` it names, not on wording. A finding that an unchecked task
+   already represents is **not** appended: it is unbuilt work that is already tracked, and
+   appending it again splits one piece of work across two IDs.
+
+   This is what makes the command idempotent. Converge run twice, or run before
+   `__SPECKIT_COMMAND_IMPLEMENT__` has worked through the list, would otherwise append the
+   same remediation tasks under fresh IDs each time — the second run cannot tell its own
+   previous output apart from the plan's original tasks.
+
+   Report the dropped ones in the summary rather than silently discarding them:
+   `F3 — already tracked by T017, not appended`. If **every** finding is already tracked,
+   there is nothing to append: take the `converged` path below and say why, so the operator
+   sees "the work is known" rather than "the codebase is complete".
 2. Write a single new section header `## Phase N: Convergence`.
 3. Emit one checklist item per actionable finding, ordered CRITICAL/HIGH first, assigning
    zero-padded IDs `T{M+1:03d}, T{M+2:03d}, …`:
diff --git a/tests/unit/test_converge_idempotency.py b/tests/unit/test_converge_idempotency.py
new file mode 100644
index 0000000000..1cd8510cc2
--- /dev/null
+++ b/tests/unit/test_converge_idempotency.py
@@ -0,0 +1,57 @@
+"""`/speckit-converge` must not append work that an unchecked task already tracks.
+
+The command's only write is appending remediation tasks to `tasks.md`. It knew how to
+compute the next task ID, but not whether a finding was already represented — so running
+it twice, or running it before `/speckit-implement` had worked through the list, appended
+the same work again under fresh IDs and split one piece of work across two entries
+(#4269). The dedup rule is what makes the command idempotent, so it is pinned here rather
+than left to survive on prose alone.
+"""
+
+from __future__ import annotations
+
+import re
+from pathlib import Path
+
+import pytest
+
+PROJECT_ROOT = Path(__file__).resolve().parent.parent.parent
+TEMPLATE = PROJECT_ROOT / "templates" / "commands" / "converge.md"
+
+
+@pytest.fixture(scope="module")
+def template_text() -> str:
+    assert TEMPLATE.is_file(), f"missing command template: {TEMPLATE}"
+    return TEMPLATE.read_text(encoding="utf-8")
+
+
+def test_the_append_step_still_exists(template_text: str) -> None:
+    """Guard against the assertions below passing vacuously if the step is renamed away."""
+    assert re.search(r"Append Convergence Tasks", template_text), (
+        "the append step is gone; the rules below no longer describe this command"
+    )
+
+
+def test_findings_are_compared_against_existing_unchecked_tasks(template_text: str) -> None:
+    assert re.search(r"unchecked task", template_text, re.IGNORECASE), (
+        "converge no longer says to compare findings against existing unchecked tasks, so "
+        "a second run appends the same work again under new IDs"
+    )
+    assert re.search(r"`- \[ \]`", template_text), (
+        "the comparison should name the marker it scans for, so the rule is executable"
+    )
+
+
+def test_the_comparison_skips_code_fences(template_text: str) -> None:
+    """Same rule the other commands apply — an example checkbox is not a tracked task."""
+    assert re.search(r"outside\s+(?:of\s+)?code\s+fences", template_text, re.IGNORECASE), (
+        "the scan must exclude fenced blocks, or a checklist documenting the checkbox "
+        "format reads as tracked work"
+    )
+
+
+def test_already_tracked_findings_are_reported_not_silently_dropped(template_text: str) -> None:
+    assert re.search(r"already tracked", template_text, re.IGNORECASE), (
+        "a finding dropped as already-tracked must be reported; dropping it silently is "
+        "indistinguishable from not having found it"
+    )