# Native identity and ownership

Source: https://libtmux.org/en/fsharp/latest/topics/ownership/

> Use the same .NET entities while making resource ownership explicit.

F# helpers operate on native .NET servers, sessions, windows, panes, requests,
and exceptions. Passing an entity between F# and C# does not require a conversion
or a second object model.

## Captured identity is retained

Local sequence operations select existing objects; they do not reacquire them.
Keep a single capture for a related set of decisions, and acquire new state
explicitly when freshness matters. A missing completed lookup can be represented
by an option. An acquisition failure remains an error, not a missing value.

Use [`Selection.exactlyOne`](<https://libtmux.org/en/fsharp/latest/reference/libtmux-fsharp-selection-exactlyone/>) when zero and multiple local matches need distinct
outcomes. See [query concepts](https://libtmux.org/en/fsharp/latest/concepts/queries/) and the
[query guide](https://libtmux.org/en/fsharp/latest/guides/queries/) for the selection rules.

## Own clients separately from daemons

| Operation | Ownership |
| --- | --- |
| [`Control.withSession`](<https://libtmux.org/en/fsharp/latest/reference/libtmux-fsharp-control-withsession/>) | Owns a control client for one task. |
| [`Control.enter`](<https://libtmux.org/en/fsharp/latest/reference/libtmux-fsharp-control-enter/>) or [`Control.enterSession`](<https://libtmux.org/en/fsharp/latest/reference/libtmux-fsharp-control-entersession/>) | Returns a client whose caller must arrange disposal. |
| [`Control.useSession`](<https://libtmux.org/en/fsharp/latest/reference/libtmux-fsharp-control-usesession/>) | Transfers a supplied client's lifetime into the task scope. |
| [`Control.foldWhile`](<https://libtmux.org/en/fsharp/latest/reference/libtmux-fsharp-control-foldwhile/>) or [`Control.iter`](<https://libtmux.org/en/fsharp/latest/reference/libtmux-fsharp-control-iter/>) | Borrows the client and disposes its own event enumerator. |

Ending a control-client scope does not grant permission to kill the tmux daemon.
When an example creates sessions on a private endpoint, it can remove those
resources as part of its own cleanup. An application connecting to an existing
server must leave that server's lifetime with its owner.

## Keep the useful failure

If an event callback and enumerator cleanup both fail, the callback exception
propagates with its original type. [`Control.cleanupFailure`](<https://libtmux.org/en/fsharp/latest/reference/libtmux-fsharp-control-cleanupfailure/>) exposes the cleanup
failure as well. This lets a handler still match the original core exception
without silently discarding the release error.

The [stream guide](https://libtmux.org/en/fsharp/latest/guides/streams/) describes consumer lifetimes and the
[.NET interoperation guide](https://libtmux.org/en/fsharp/latest/guides/interop/) covers native types and
exceptions. The [transport examples](https://libtmux.org/en/fsharp/latest/concepts/transports/) put acquisition,
use, and cleanup together in complete programs.