[tleonhardt]

Summary

Follow-up to #1795. A review of that change found that a single session_start_index can't describe the session once the list is changed in place. This PR changes how History tracks the session.

History now records which entries were present when start_session() ran. Unbounded ranges, str_search(), regex_search(), and the history --run/--edit --all guard all check that membership. Moving, filtering, or repeating entries therefore keeps persisted commands persisted and new entries current. This replaces the six list mutator overrides added in #1795.

Problems fixed

Using 4 persisted entries (o0–o3) followed by 2 current entries (n0, n1):

Operation	Before	After
reverse()	current session = o1, o0	n1, n0
sort() ascending by raw	current session = o2, o3	n0, n1
history *= 2 / history += list(history)	copies of o0–o3 counted as current	only n0, n1 copies are current
history --run 5:6 after reverse()	replayed persisted commands without --all	refused: "Use --all to run or edit commands from previous sessions."
history[:] = [history[1], new] right after start_session()	new hidden as persisted	new is current
history[:] = [n0, o1, n1]	o1 counted as current	o1 stays persisted

Behavior notes

• New entries belong to the current session wherever they are inserted or assigned. Previously, a new entry placed before the old boundary was counted as persisted.
• Membership belongs to the entry object. Appending the same persisted HistoryItem object again keeps it persisted. To record a persisted command again in the current session, append its statement (history.append(history[i].statement)). This is documented in History.is_persisted().
• session_start_index is now a computed property: the index just past the last persisted entry. Every entry from that index on is current. Assigning it still marks the first n entries as persisted, so existing callers and tests that set it keep working.
• Membership survives copy.deepcopy() and pickling. It is keyed by an identity wrapper rather than raw id() values, so copies and unpickled histories still recognize their persisted entries.
• Adds public History.is_persisted(item).

Tests

• tests/test_history_mutations.py was rewritten around a current_session() helper. It returns {command number: raw} and checks that span(":"), str_search(), and regex_search() agree. It also checks the session_start_index rule. Expected values are hand-derived literals.
• New tests cover reverse/sort/*=/+=, assignment into an empty session, persisted entries placed after current ones, inserts at any position, re-appending a persisted object, deepcopy/pickle, and the --all guard after reordering and repetition. Each failed on main before the change.
• Removed test_remove_retains_native_list_dispatch and test_failed_straddling_replacement_preserves_history, which tested the internals of the deleted overrides. Failed mutations are still covered by test_failed_mutation_preserves_history_and_membership.

Test plan

• make check (ruff, prettier, typos, ty, mypy)
• make test: 2924 passed, 3 skipped; cmd2/history.py at 100% coverage
• make docs-test

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.75%. Comparing base (226c3b7) to head (99d806e).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1798      +/-   ##
==========================================
- Coverage   99.75%   99.75%   -0.01%     
==========================================
  Files          23       23              
  Lines        6624     6592      -32     
==========================================
- Hits         6608     6576      -32     
  Misses         16       16              

Flag	Coverage Δ
unittests	99.75% <100.00%> (-0.01%)	⬇️

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