[tony]

PaneObservation.capture(pane) retains sampled pane text after redraw or removal. It copies lines and the actual command argv into a frozen standalone value, retaining capture selection and the controller's monotonic interval without live pane/server references.

The call uses the supplied pane.cmd route and refuses failed or oversized captures instead of returning a successful empty value. The decoded-text admission limit counts Python Unicode code points and LF, after the existing transport returns. It is not a transport memory cap or an added deadline. Pane lifetime remains explicitly unknown with the legacy handle.

This is the independent pane-value slice of #370 under #629, based on current master with sibling branches absent. PR #568 still retains mutable nested lists/dicts; #587/#590 cover inherited object graphs and #613 covers mutable ASCII rendering and pytest integration. Their wider work remains open. This slice adds no engine classes, object graph, serializer or persistent recording.

Validation:

• Owned noninteractive producer on tmux 3.2a and local 3.8a; retained Unicode text after pane removal, missing-pane failure and borrowed-server survival.
• Custom command routing, immutable text/argv aliases, codepoint/LF admission, native errors and unknown lifetime.
• Deliberately retaining the mutable source list makes the critical regression fail.
• Actual proposed engine with a deliberately different facade endpoint routes to the selected borrowed engine; that engine remains usable.
• Disposable composition with PR command(feat[timeout]) Add opt-in per-call deadlines #807; each slice also builds independently.
• Ruff, full-tree mypy, doctest, Sphinx docs and fresh whole-branch review.
• Complete suite: 1,439 passed, 3 skipped; the same 18 hooks/popup/floating failures already reproduced on unchanged master remain, without reruns.
• All eight hosted tmux build lanes (3.2a through master), CodeQL and coverage at the PR head.

Retained values remain readable while referenced, including after server loss; process exit loses the in-memory value. Captures cannot establish omitted-output continuity, hidden terminal state, or arbitrary-shell completion. No macOS work or minimum-version change is included; existing support remains unchanged.

Refs #370. Keep its broader graph, serialization and observation criteria open.

[codecov]

Codecov Report

❌ Patch coverage is 63.26531% with 18 lines in your changes missing coverage. Please review.
✅ Project coverage is 52.51%. Comparing base (0813d07) to head (d794cc8).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
src/libtmux/observation.py	63.26%	17 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #810      +/-   ##
==========================================
+ Coverage   52.45%   52.51%   +0.06%     
==========================================
  Files          26       27       +1     
  Lines        3729     3778      +49     
  Branches      747      757      +10     
==========================================
+ Hits         1956     1984      +28     
- Misses       1469     1489      +20     
- Partials      304      305       +1     

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