diff --git a/src/claire/orchestrator/tools.py b/src/claire/orchestrator/tools.py
index bc775b7..8d3d7a6 100644
--- a/src/claire/orchestrator/tools.py
+++ b/src/claire/orchestrator/tools.py
@@ -400,18 +400,42 @@ def send_to_session(
     session_ref: str,
     text: str,
 ) -> dict[str, Any]:
-    """Send text directly to one session, bypassing project-broadcast."""
+    """Send text directly to one session, bypassing project-broadcast.
+
+    Targets the session by its `tmux_name`: `rclaude send --match` matches
+    tmux *session names*, never Claude session UUIDs, so passing a UUID
+    there silently matches nothing. The session's `tmux_name` is populated
+    by the pull loop (for resumed sessions) or by `dispatch_task` (for
+    freshly-spawned ones). If it's still unknown, fail loudly rather than
+    fire a send that would match nothing.
+    """
     try:
         sid = service.resolve_session_id(conn, session_ref)
     except (service.NotFound, service.InvalidInput) as exc:
         raise ToolError(str(exc)) from exc
+    session = read.get_session(conn, sid)
+    if session is None:
+        raise ToolError(
+            f"session {sid} has no projection row yet — run `pull` first so "
+            f"its tmux_name can be resolved"
+        )
+    if not session.tmux_name:
+        raise ToolError(
+            f"session {sid} has no known tmux_name — it has not been observed "
+            f"as a live tmux pane (run `pull`, or the session may not be "
+            f"running). `rclaude --match` cannot target a session by UUID."
+        )
     from ..rclaude import Rclaude, RclaudeError
     rcl = Rclaude()
     try:
-        rcl.send(text=text, match=str(sid)[:8], yes=True, dry_run=False)
+        rcl.send(text=text, match=session.tmux_name, yes=True, dry_run=False)
     except RclaudeError as exc:
         raise ToolError(f"rclaude send failed: {exc}") from exc
-    return {"session_uuid": str(sid), "delivered": True}
+    return {
+        "session_uuid": str(sid),
+        "tmux_name": session.tmux_name,
+        "delivered": True,
+    }
 
 
 # ---------------------------------------------------------------------------
diff --git a/src/claire/pull.py b/src/claire/pull.py
index 85548be..e47856e 100644
--- a/src/claire/pull.py
+++ b/src/claire/pull.py
@@ -52,6 +52,12 @@ def _session_snapshot(
     return {UUID(r["uuid"]): (r["host"], r["cwd"], r["last_seen_mtime"]) for r in rows}
 
 
+def _tmux_name_snapshot(conn: sqlite3.Connection) -> dict[UUID, str | None]:
+    """Return {uuid: tmux_name} from the sessions table — for the tmux-mapping diff."""
+    rows = conn.execute("SELECT uuid, tmux_name FROM sessions").fetchall()
+    return {UUID(r["uuid"]): r["tmux_name"] for r in rows}
+
+
 def _triage_snapshot(
     conn: sqlite3.Connection,
 ) -> dict[UUID, tuple[int | None, str | None, str | None]]:
@@ -146,6 +152,42 @@ def pull(
     except RclaudeError as exc:
         errors.append(f"list_tmux: {exc}")
         tmux_rows = []
+
+    # --- UUID → tmux_name mapping -----------------------------------------
+    # A tmux pane started via `claude --resume <uuid>` carries that UUID in
+    # its `resumed_uuid` column. That's the only signal that resolves a
+    # *specific* session UUID to a live tmux session name (the tmux name
+    # itself encodes only the cwd slug). Without it, `send_to_session` can't
+    # target a session — `rclaude --match` matches tmux names, never UUIDs.
+    # Emit a SessionObserved carrying `tmux_name` so the projection's
+    # `sessions.tmux_name` column gets populated. Diff against the current
+    # projection so we only emit when the mapping actually changed; only set
+    # tmux_name when known (the COALESCE in the projection never clobbers a
+    # known name with None).
+    tmux_name_snap = _tmux_name_snapshot(conn)
+    for trow in tmux_rows:
+        if not trow.resumed_uuid:
+            continue
+        try:
+            mapped_uuid = UUID(trow.resumed_uuid)
+        except ValueError:
+            errors.append(f"list_tmux: bad resumed_uuid {trow.resumed_uuid!r}")
+            continue
+        if tmux_name_snap.get(mapped_uuid) == trow.session_name:
+            continue
+        events.append(
+            conn,
+            generator,
+            events.SessionObserved(
+                session_uuid=mapped_uuid,
+                host=trow.host,
+                cwd=None,
+                tmux_name=trow.session_name,
+                last_seen_mtime=None,
+            ),
+        )
+        sessions_observed += 1
+
     # Slug used in tmux names mirrors rclaude's: leading slashes/tildes
     # stripped, non-alphanumeric → '-'.
     def _slug(s: str) -> str:
diff --git a/src/claire/rclaude.py b/src/claire/rclaude.py
index a26fd44..7a7e1ab 100644
--- a/src/claire/rclaude.py
+++ b/src/claire/rclaude.py
@@ -53,6 +53,10 @@ class TmuxRow:
     host: str
     session_name: str
     detail: str
+    # The Claude session UUID this tmux pane was started with via
+    # `claude --resume <uuid>`. `None` for fresh-spawned panes (no --resume)
+    # or for output from an older rclaude that doesn't emit the 5th column.
+    resumed_uuid: str | None = None
 
 
 @dataclass(frozen=True)
@@ -144,7 +148,9 @@ class Rclaude:
     def list_tmux(self) -> list[TmuxRow]:
         """Cross-host live tmux sessions via `rclaude list tmux --tsv`.
 
-        Raw TSV row shape: `host\\ttmux\\tsession_name\\tdetail`.
+        Raw TSV row shape: `host\\ttmux\\tsession_name\\tdetail\\tresumed_uuid`.
+        The 5th column (`resumed_uuid`) is additive — rows from an older
+        rclaude with only 4 columns are tolerated, mapping to `None`.
         """
         raw = self._run(["list", "tmux", "--tsv"])
         rows: list[TmuxRow] = []
@@ -154,11 +160,13 @@ class Rclaude:
             parts = line.split("\t")
             if len(parts) < 3 or parts[1] != "tmux":
                 continue
+            resumed = parts[4].strip() if len(parts) >= 5 and parts[4].strip() else None
             rows.append(
                 TmuxRow(
                     host=parts[0],
                     session_name=parts[2],
                     detail=parts[3] if len(parts) >= 4 else "",
+                    resumed_uuid=resumed,
                 )
             )
         return rows
diff --git a/src/claire/web/service.py b/src/claire/web/service.py
index 6760682..6151ad9 100644
--- a/src/claire/web/service.py
+++ b/src/claire/web/service.py
@@ -412,8 +412,16 @@ def broadcast(
     failed = 0
     errors: list[str] = []
     for sid in session_uuids:
+        # `rclaude --match` matches tmux session names, never Claude UUIDs —
+        # resolve each session to its `tmux_name` before targeting. A session
+        # with no known tmux_name can't be reached; surface that as a failure.
+        session = read.get_session(conn, UUID(sid))
+        if session is None or not session.tmux_name:
+            failed += 1
+            errors.append(f"{sid}: no known tmux_name (not observed as a live pane)")
+            continue
         try:
-            rcl.send(text=text, match=sid[:8], yes=yes, dry_run=not yes)
+            rcl.send(text=text, match=session.tmux_name, yes=yes, dry_run=not yes)
             delivered += 1
         except RclaudeError as exc:
             failed += 1
@@ -1435,6 +1443,23 @@ def dispatch_task(
             "session spawned but not discovered within timeout",
         )
 
+    # Record the UUID → tmux_name mapping for this fresh session. A freshly
+    # spawned pane has no `claude --resume <uuid>` in its start command, so
+    # the pull loop's resumed_uuid mapping will never see it — but dispatch
+    # knows both the new UUID and the tmux name it spawned. Emitting this now
+    # makes the dispatched agent addressable via `send_to_session` (which
+    # resolves UUID → tmux_name → `rclaude send --match`).
+    ev.append(
+        conn,
+        gen,
+        ev.SessionObserved(
+            session_uuid=UUID(new_uuid),
+            host=host,
+            cwd=cwd,
+            tmux_name=tmux_name,
+        ),
+    )
+
     assignment = create_assignment(
         conn, gen, task_id=task_id, session_uuid=UUID(new_uuid),
     )
diff --git a/tests/test_pull_idempotency.py b/tests/test_pull_idempotency.py
index 611d9f8..a544f50 100644
--- a/tests/test_pull_idempotency.py
+++ b/tests/test_pull_idempotency.py
@@ -14,21 +14,27 @@ from __future__ import annotations
 from uuid import UUID
 
 from claire.pull import pull
-from claire.rclaude import SessionRow, TriageRow
+from claire.rclaude import SessionRow, TmuxRow, TriageRow
 
 
 class _FakeRclaude:
     """Deterministic rclaude stand-in returning the same rows every call."""
 
-    def __init__(self, sessions: list[SessionRow], triage: list[TriageRow] | None = None):
+    def __init__(
+        self,
+        sessions: list[SessionRow],
+        triage: list[TriageRow] | None = None,
+        tmux: list[TmuxRow] | None = None,
+    ):
         self._sessions = sessions
         self._triage = triage or []
+        self._tmux = tmux or []
 
     def list_sessions(self) -> list[SessionRow]:
         return list(self._sessions)
 
-    def list_tmux(self) -> list:
-        return []  # no live panes in this idempotency test
+    def list_tmux(self) -> list[TmuxRow]:
+        return list(self._tmux)
 
     def triage(self) -> list[TriageRow]:
         return list(self._triage)
diff --git a/tests/test_rclaude_wrapper.py b/tests/test_rclaude_wrapper.py
index f47eb46..8a2ff3f 100644
--- a/tests/test_rclaude_wrapper.py
+++ b/tests/test_rclaude_wrapper.py
@@ -48,6 +48,36 @@ def test_rclaude_list_tmux_parses_tsv(monkeypatch: pytest.MonkeyPatch) -> None:
     assert rows[1].host == "apricot"
 
 
+def test_rclaude_list_tmux_parses_resumed_uuid(monkeypatch: pytest.MonkeyPatch) -> None:
+    """The 5th TSV column (resumed_uuid) is parsed when present."""
+    monkeypatch.setattr("shutil.which", lambda _: "/usr/local/bin/rclaude")
+    output = (
+        # resumed session — has the 5th column
+        "local\ttmux\tclaude-natalie-foo-1715964800\t1 windows\t"
+        "08381960-ecca-49eb-9d6e-9f0c505e8f9e\n"
+        # fresh-spawned session — 5th column present but empty
+        "apricot\ttmux\tclaude-natalie-bar-1715964900\t2 windows\t\n"
+    )
+    rcl = Rclaude(runner=_fake_runner(stdout=output))
+    rows = rcl.list_tmux()
+    assert len(rows) == 2
+    assert rows[0].resumed_uuid == "08381960-ecca-49eb-9d6e-9f0c505e8f9e"
+    assert rows[1].resumed_uuid is None
+
+
+def test_rclaude_list_tmux_tolerates_missing_5th_column(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    """Output from an older rclaude (only 4 columns) maps resumed_uuid to None."""
+    monkeypatch.setattr("shutil.which", lambda _: "/usr/local/bin/rclaude")
+    output = "local\ttmux\tclaude-natalie-foo-1715964800\t1 windows (created ...)\n"
+    rcl = Rclaude(runner=_fake_runner(stdout=output))
+    rows = rcl.list_tmux()
+    assert len(rows) == 1
+    assert rows[0].session_name == "claude-natalie-foo-1715964800"
+    assert rows[0].resumed_uuid is None
+
+
 def test_rclaude_list_sessions_parses_tsv(monkeypatch: pytest.MonkeyPatch) -> None:
     monkeypatch.setattr("shutil.which", lambda _: "/usr/local/bin/rclaude")
     # `rclaude list sessions --tsv` interleaves tmux rows with session rows;