fix(plugins): make the install marker durable before claim_install returns

Review nit from @karthik-indla on this PR. A hard kill between the O_EXCL open
and the buffered write reaching disk left a marker that exists but parses to
nothing: is_first_run reads it as claimed, so that install is never counted, and
claim_version_change cannot read a version out of it.

Not temp-and-rename, which is what the equivalent fixes in this stack use: the
O_EXCL open is what makes this claim exclusive across concurrently starting
sessions, and a rename would clobber rather than lose the race. The content is
the part that needed making safe, so it is flushed and fsynced before the call
returns.

The recovery path stays as the backstop: _repair_install_state already rewrites
an unparseable marker so version tracking resumes.

304 passed, 8 skipped.

Claude-Session: https://claude.ai/code/session_01C7tEmH86HAr7GoAAKCEHZb

integrations/agent-plugin-core/python/telemetry.py

@@ -370,6 +370,14 @@ def claim_install(was_empty: bool | None = None) -> str | None:
                 },
                 stream,
             )
+            # Durable before this returns. The O_EXCL open is what makes the
+            # claim exclusive, so it cannot be replaced by a temp-and-rename
+            # without losing that, which leaves the content as the thing to make
+            # safe. A kill between the open and this fsync used to leave a marker
+            # that exists but parses to nothing: is_first_run reads it as claimed
+            # and claim_version_change cannot read a version out of it.
+            stream.flush()
+            os.fsync(stream.fileno())
     except OSError:
         pass
     return "upgrade" if upgrading else "install"

integrations/antigravity-plugin/core/telemetry.py

@@ -370,6 +370,14 @@ def claim_install(was_empty: bool | None = None) -> str | None:
                 },
                 stream,
             )
+            # Durable before this returns. The O_EXCL open is what makes the
+            # claim exclusive, so it cannot be replaced by a temp-and-rename
+            # without losing that, which leaves the content as the thing to make
+            # safe. A kill between the open and this fsync used to leave a marker
+            # that exists but parses to nothing: is_first_run reads it as claimed
+            # and claim_version_change cannot read a version out of it.
+            stream.flush()
+            os.fsync(stream.fileno())
     except OSError:
         pass
     return "upgrade" if upgrading else "install"

integrations/claude-code-plugin/core/telemetry.py

@@ -370,6 +370,14 @@ def claim_install(was_empty: bool | None = None) -> str | None:
                 },
                 stream,
             )
+            # Durable before this returns. The O_EXCL open is what makes the
+            # claim exclusive, so it cannot be replaced by a temp-and-rename
+            # without losing that, which leaves the content as the thing to make
+            # safe. A kill between the open and this fsync used to leave a marker
+            # that exists but parses to nothing: is_first_run reads it as claimed
+            # and claim_version_change cannot read a version out of it.
+            stream.flush()
+            os.fsync(stream.fileno())
     except OSError:
         pass
     return "upgrade" if upgrading else "install"

integrations/codex-plugin/core/telemetry.py

@@ -370,6 +370,14 @@ def claim_install(was_empty: bool | None = None) -> str | None:
                 },
                 stream,
             )
+            # Durable before this returns. The O_EXCL open is what makes the
+            # claim exclusive, so it cannot be replaced by a temp-and-rename
+            # without losing that, which leaves the content as the thing to make
+            # safe. A kill between the open and this fsync used to leave a marker
+            # that exists but parses to nothing: is_first_run reads it as claimed
+            # and claim_version_change cannot read a version out of it.
+            stream.flush()
+            os.fsync(stream.fileno())
     except OSError:
         pass
     return "upgrade" if upgrading else "install"

integrations/cursor-plugin/core/telemetry.py

@@ -370,6 +370,14 @@ def claim_install(was_empty: bool | None = None) -> str | None:
                 },
                 stream,
             )
+            # Durable before this returns. The O_EXCL open is what makes the
+            # claim exclusive, so it cannot be replaced by a temp-and-rename
+            # without losing that, which leaves the content as the thing to make
+            # safe. A kill between the open and this fsync used to leave a marker
+            # that exists but parses to nothing: is_first_run reads it as claimed
+            # and claim_version_change cannot read a version out of it.
+            stream.flush()
+            os.fsync(stream.fileno())
     except OSError:
         pass
     return "upgrade" if upgrading else "install"

integrations/kimi-plugin/core/telemetry.py

@@ -370,6 +370,14 @@ def claim_install(was_empty: bool | None = None) -> str | None:
                 },
                 stream,
             )
+            # Durable before this returns. The O_EXCL open is what makes the
+            # claim exclusive, so it cannot be replaced by a temp-and-rename
+            # without losing that, which leaves the content as the thing to make
+            # safe. A kill between the open and this fsync used to leave a marker
+            # that exists but parses to nothing: is_first_run reads it as claimed
+            # and claim_version_change cannot read a version out of it.
+            stream.flush()
+            os.fsync(stream.fileno())
     except OSError:
         pass
     return "upgrade" if upgrading else "install"

integrations/mem0-agent-plugin/core/telemetry.py

@@ -370,6 +370,14 @@ def claim_install(was_empty: bool | None = None) -> str | None:
                 },
                 stream,
             )
+            # Durable before this returns. The O_EXCL open is what makes the
+            # claim exclusive, so it cannot be replaced by a temp-and-rename
+            # without losing that, which leaves the content as the thing to make
+            # safe. A kill between the open and this fsync used to leave a marker
+            # that exists but parses to nothing: is_first_run reads it as claimed
+            # and claim_version_change cannot read a version out of it.
+            stream.flush()
+            os.fsync(stream.fileno())
     except OSError:
         pass
     return "upgrade" if upgrading else "install"