Remove the height-independence opt-in flags; always use declared ones

evidence/native-height-declaration-admission-20261005/SCOPE.md

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+# Height reuse from the original measurement declaration
+
+Base: merged66/main9ea7a109b648be526ce5d000b2c94799b57f3c23.
+Frozen66/0945 and65/e253 source/control/artifacts remain immutable.
+
+Existing HeightDependency, Widget class binding and Layout class binding already
+own the selected measurement/arrangement's available-height dependency. Widget
+arrange and box resolution ask those same owners but only after a separate
+CACHE_HEIGHT_INDEPENDENT_BOX/ARRANGEMENT class flag grants reuse. That repeats
+an independently supplied decision across native and Toad subclasses and leaves
+ordinary declared-independent containers remeasuring unchanged width/source.
+
+Remove both flags, their native subclass declarations and every native gate/test
+reader. Existing proof/resource invalidation becomes load bearing by default.
+No new class, mapping, cache, state flag, threshold or alternate algorithm.
+Unknown/custom method/layout/scalar/relative-height proofs remain conservative;
+original viewport, width, parent source/auto-size inputs and native revisions
+remain. Dynamic instance method replacement has no class-declared proof: this
+change does not manufacture a proof for arbitrary monkeypatches.
+
+Claims: Widget.arrange/_get_box_model class-flag gate family, native containers
+and existing affected source controls. Heis owns all15 Toad declaration removals
+in the future paired successor; current455 purpose/source stays untouched.
+Einstein456 preparation completion is disjoint; no Toad writes by this contributor.
+
+Original436 Down78.432014329 observed nested native reflow/arrange/content-height
+calls. Its profile observes execution, not redundancy, per-call duration or CPU
+share. Source identifies the separate flag bypass of existing proof authority.
+Current scroll measurement epochs already exclude mere scroll placement; do not
+remove them or genuine custom/relative-height dependencies for this change.
+
+Complete before AST from original Package loader covers native production/tests
+and Toad production/tests/tools with no parse omissions (before.json). AST alone
+cannot prove dynamic dispatch or arbitrary external aliases. Read original owner,
+class initialization, proof family and all flag consumers before implementation.
+Pattern IMPL-5: duplicate authorization of one declared measurement relation.
+
+At the initial source checkpoint this was source-only/Draft/untested. Later
+named source App authorization and qualification are recorded below; installed
+pairing remains separate. Existing oracle controls will compare warmed results against original
+fresh calculation after cache clear, not retain a second opt-in switch.
+
+
+## Coherent implementation checkpoint
+
+Widget.arrange always borrows its existing source-epoch height-dependency proof;
+its original resource key retains width, viewport, NodeList/layout source,
+optimal mode and dependency result. The actual calculation receives the original
+size, never the normalized cache key. Widget._get_box_model similarly borrows
+its existing selected proof; only proven-unused incoming-height key inputs are
+normalized. Original parent revision/auto-size inputs and all source invalidation
+remain unchanged. No measurement or style proof algorithm is relaxed.
+
+Deleted both Widget opt-in declarations and both decisions plus all four native
+VerticalGroup/HorizontalGroup labels. Existing controls now instantiate original
+native classes rather than four empty opt-in wrapper classes. Reference results
+come from original fresh calculation after cache clear for each input; warmed
+results compare against those exact originals. Custom measurement/layout/extent/
+scalar/hook, stream/grid/docking, viewport/relative-height, raw mutation, parent
+auto-sizing and scroll/retirement controls stay in the affected source family.
+No alternate raw measurement algorithm, new test toggle or proof mirror.
+
+All original native source/test flag consumers are gone. Heis owns deletion of
+15 remaining Toad class labels in the future paired successor; they are explicitly
+unfinished consumer cleanup, not current455 edits. Native dependencies remain
+class-declared through original subclass initialization: arbitrary later runtime
+monkeypatch rebinding is an unresolved external dynamic boundary, not a proven
+native reuse contract. No public input or installed runtime was changed.
+
+At implementation checkpoint455d8ec2 only source syntax/diff was checked. No
+controls/App/wheel/dependency/prefix/SDK/provider/recording had run. Subsequent
+changed source App qualification is below; installed pairing remains unqualified.
+
+
+## Changed native source App qualification
+
+Executed source/controlb158ca382f835db4351d920eef6c16f77490b2c6; production
+455d8ec2d0339e1f0ddba2634361c7aebf86386e. ONE originally authorized source App
+batch: **62PASS/4.51s pytest**,5.604s controller, exit0. Exact argv/interpreter/raw
+output/hash are source-batch01.json and source-batch01.log. Existing system
+/usr/bin/python and dependencies, PYTHONPATH=src; no new environment/installation.
+
+The two existing modules retain fresh original calculation versus warmed reuse,
+width/viewport/optimal/parent inputs, full source mutation/inherited style/display/
+structural admission and scroll retirement. Custom measurement/layout/hooks,
+scalar resolvers, relative/fractional/extrema, stream/grid/automatic sizing keep
+conservative context. These 62 source App cases pass without either retired flag
+or label-only wrapper class. No failed case or rerun; accepted66 compositor22
+and frozen65 controls not repeated.
+
+This confirms the changed native source family, not installed Toad/body/wheel,
+Linux motion, frame cadence, cold traversal cost, CPU gain or full performance.
+New proof acquisition has a real cold traversal; existing source-epoch reuse is
+not a measured speedup. Heis owns remaining15Toad declaration deletions and the
+future coherent affected paired application scope; current455 bytes/artifacts
+stay frozen. No current holder, wheel, SDK/provider, film or package purpose.

evidence/native-height-declaration-admission-20261005/after.json

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+{
+  "head": "455d8ec2d0339e1f0ddba2634361c7aebf86386e",
+  "roots": [
+    {
+      "root": "src/textual",
+      "parsed": 249,
+      "omitted": []
+    },
+    {
+      "root": "tests",
+      "parsed": 460,
+      "omitted": []
+    }
+  ],
+  "retired_flags": [],
+  "proof_declarations": [
+    {
+      "path": "src/textual/widget.py",
+      "line": 1880,
+      "name": "_arrangement_depends_on_available_height"
+    },
+    {
+      "path": "src/textual/widget.py",
+      "line": 1899,
+      "name": "_box_depends_on_available_height"
+    }
+  ],
+  "proof_calls": [
+    {
+      "path": "src/textual/_measurement.py",
+      "line": 93,
+      "source": "widget._arrangement_depends_on_available_height()"
+    },
+    {
+      "path": "src/textual/_measurement.py",
+      "line": 134,
+      "source": "child._box_depends_on_available_height()"
+    },
+    {
+      "path": "src/textual/widget.py",
+      "line": 1418,
+      "source": "self._arrangement_depends_on_available_height()"
+    },
+    {
+      "path": "src/textual/widget.py",
+      "line": 1934,
+      "source": "self._box_depends_on_available_height()"
+    }
+  ],
+  "limits": [
+    "AST name matching is not arbitrary external/dynamic alias proof. Toad15 label deletions remain Heis-owned future paired work; current455 stays frozen. Class-contract binding and source invalidation remain original."
+  ]
+}