Arc 7's last step. Stages 1, 2A, 2B-1, 2B-2 and 2B-3 are all on main;
the panel is complete on both frontends and every mechanism this stage
needs exists. What remains is the decision the arc deferred on purpose:
omitting `display` should mean the panel, not the selected window.
Revision 2, approved with amendments. The scout found the parent
framing's plan sound and two of its details drifted.
THE FLIP IS THREE SITES IN TWO LANGUAGES, and a fourth validator that
must not move. `parse_adopter_placement` reads like the shared parser
its doc comment implies but has EXACTLY ONE CALLER, the terminal;
listview and compile each re-implement the same three-value validation
in Lua, including their own copy of the error message. Changing only
the Rust parser would leave both Lua adopters resolving omission to the
current window — a half-flip that looks done and behaves inconsistently
per adopter.
DIRED IS A FOURTH COPY OF THE VALIDATOR AND MUST KEEP `"current"`.
Review caught this; revision 1 had it as a leaning. The mechanism is
specific rather than stylistic: `pmacs.path.set_directory_handler`
passes `{ dest = dest }` with NO `display` key, so `pmacs .` resolves
by omission. Flipping dired's default would open the golden journey's
first directory listing in a bottom panel. The distinction that makes
this principled rather than an exception: listview, compile and terminal
produce output the user CONSULTS; dired produces a document the user
WORKS IN. The panel default is right for the first kind and wrong for
the second.
UNIFY NARROWLY, NOT WHOLESALE. A shared
`resolve_adopter_display(operation, raw, default)` owns the vocabulary,
the error text and the default policy, with dired passing
`default = "current"` so its exemption is a parameter rather than a
divergent copy. Terminal's `window` mutual-exclusion stays in its Rust
wrapper — the parsers are not identical and a helper pretending
otherwise would be its own defect.
One normalization is named rather than absorbed: terminal reads
`get::<Option<String>>("display")?`, so a non-string value raises mlua's
TYPE error before the custom "unknown display" message, while the Lua
callers `tostring()` it into their own. Different observable behaviour
for the same bad input; unifying the error text without deciding this
would silently change one of them.
`select` IS A CORRECTNESS REQUIREMENT, and Q#BP12's citation drifted.
`seat_cursor` is at listview.lua:130, not :64 — :64 is now a name-variant
constant. The constraint holds and is worse than "focus preference":
`seat_cursor` drives `pmacs.editor.move_down()`, which acts on the ACTIVE
window, so an unselected listview panel seats the cursor in the user's
document. That is why the table's `select` differs per adopter —
listview true, compile false, terminal true — and why a uniform value
would look right and break compile's passive output.
TESTS ARE MEASURED BEFORE THE FLIP, NOT AFTER. Two Stage 1 acceptance
tests assert the old default deliberately: acc19 (:1223) opens a
listview with no `display` specifically to seed a DOCUMENT window "so
side-affine placement cannot be vacuous" — the flip breaks its
anti-vacuity guarantee, not merely its assertion — and acc19b (:1308) is
built around a recompile reaching `start_run` with no `display`. The
sweep rule is stated: a test whose SUBJECT is placement asserts the new
default; a test whose subject is compile or terminal behaviour opts out
only when its setup genuinely requires the document window. Mass-adding
`display = "current"` to make suites green would convert a behavioural
change into an invisible one.
Acceptance gains a NEGATIVE criterion (9): omitted `display` still means
document placement for direct dired AND for `pmacs .`. That is the
criterion that catches a well-intentioned "make all four consistent"
change.
Framing only. No code, no flip, no test changes.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Levi Neuwirth
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