Deduplicate use of Tightness as both an element and a simple type

.claude/CLAUDE.md

@@ -0,0 +1 @@
+@../AGENTS.md

.github/copilot-instructions.md

@@ -0,0 +1,5 @@
+# BuildingSync Schema - Copilot Instructions
+
+All repository rules for AI agents live in [AGENTS.md](../AGENTS.md). Read and follow it before making changes.
+
+File-scoped rules in [.github/instructions/](instructions/) apply automatically to `BuildingSync.xsd` and `proposals/**/*.md`.

.github/instructions/proposals.instructions.md

@@ -0,0 +1,15 @@
+---
+applyTo: "proposals/**/*.md"
+description: "Format and process for BuildingSync feature proposals"
+---
+
+# Writing a proposal
+
+Follow [proposals/README.md](../../proposals/README.md).
+
+- Location: `proposals/<year of submission>/<Title Case Name>.md` (e.g. `proposals/2026/Add Field-assembled DX system to DXSystemType.md`).
+- Required sections, in order: `## Overview` (brief summary), `## Justification` (evidence the change is needed and beneficial), `## Implementation` (exact XSD changes: element paths, types, enumerations, documentation text). Optional: `## References`.
+- State whether the change is breaking or non-breaking per [docs/versioning.md](../../docs/versioning.md); breaking proposals must discuss severity of the breakage and the migration path.
+- Reference the GitHub issue it addresses.
+- Proposal PRs are discussed and accepted/rejected before (or alongside) the implementation PR; the project lead decides if no consensus.
+- Markdown is formatted by prettier via `poetry run pre-commit run --all-files`.

.github/instructions/schema-xsd.instructions.md

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+---
+applyTo: "BuildingSync.xsd"
+description: "Conventions for editing the BuildingSync XSD"
+---
+
+# Editing BuildingSync.xsd
+
+Read the surrounding region first and keep edits minimal; do not reformat unrelated content. Classify the change (breaking / non-breaking / patch, per [docs/versioning.md](../../docs/versioning.md)) before editing.
+
+## Structure
+
+- Indent with 2 spaces, never tabs; no XMLSpy comments (run `bundle exec rake remove_tabs` after editing).
+- Never use `xs:complexContent` (test-enforced); compose with named types, `xs:sequence`, and `ref`.
+- New elements are optional (`minOccurs="0"`) unless a breaking change is intended and approved.
+- Inserting a new optional element into an `xs:sequence` is fine; moving or reordering existing elements is breaking.
+- `xs:element` names must be unique across the schema. To reuse a structure, define a named `xs:complexType`/`xs:simpleType` (suffix `Type`) or a global element used via `ref="auc:..."`.
+- Global names must not collide with gbXML global names.
+- Do not modify the header (`version` attribute, title documentation, root `version` enumeration) outside a release; see [docs/release_instructions.md](../../docs/release_instructions.md).
+
+## Documentation
+
+- Every new element, type, and enumeration-bearing element gets `<xs:annotation><xs:documentation>`.
+- Write a clear definition sentence; put units in parentheses at the end, e.g. `... gross floor area. (ft2)`, `(kBtu/ft2)`, `($)`, `(cfm)`, `(W/ft2)`.
+- Documentation-only changes are patch-level.
+
+## Enumerations
+
+- Adding a value is non-breaking; removing or renaming one is breaking (deprecate instead).
+- Follow the existing wording/casing style of sibling values; include `Other` and `Unknown` where siblings do.
+
+## Common patterns
+
+- Identity: `<xs:attribute name="ID" type="xs:ID" use="required"/>`.
+- Links: element with `<xs:attribute name="IDref" type="xs:IDREF" use="required"/>`; document the valid target in [docs/linking_elements.md](../../docs/linking_elements.md).
+- Data provenance: `<xs:attribute ref="auc:Source"/>`; system state: `ref="auc:Status"`.
+- Extensibility: `<xs:element ref="auc:UserDefinedFields" minOccurs="0"/>`.
+- gbXML content uses the `gbxml` prefix (see [docs/gbXML_reference.md](../../docs/gbXML_reference.md)).
+
+## Deprecation
+
+- Never remove elements outside a major version (XSD header Rule #1).
+- Mark deprecated items in documentation: `WARNING: This element is being deprecated, use <Replacement> instead.` (for enum values: `WARNING: This enumeration is being deprecated, use ... instead`).
+- Update examples to use the replacement.
+
+## Verify
+
+`bundle exec rake` and `bundle exec rake generate_data_dictionary` must pass.

.gitignore

@@ -49,3 +49,4 @@ gbxml.xsd
 *.bak
 *.backup
 *.tmp
+/tmp

AGENTS.md

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+# BuildingSync Schema - AI Agent Instructions
+
+This is the canonical instruction file for AI coding agents (Copilot, Claude Code, Codex, Cursor, etc.). `.claude/CLAUDE.md` and `.github/copilot-instructions.md` point here.
+
+BuildingSync is an XML schema (`BuildingSync.xsd`, namespace prefix `auc`) for exchanging building energy audit and building characteristics data. Every change must keep historical documents and downstream tools (Audit Template, Use Case Validator, BuildingSync-gem, bsyncpy, website schema viewer) working unless a major version bump is intended.
+
+## Repository layout
+
+| Path                                          | Purpose                                                                                                |
+| --------------------------------------------- | ------------------------------------------------------------------------------------------------------ |
+| `BuildingSync.xsd`                            | The schema (single file). Imports gbXML v6.01 via URL.                                                 |
+| `examples/*.xml`                              | Example instances. All must validate (except files named `*Invalid Schema*`).                          |
+| `proposals/<YEAR>/*.md`                       | Feature proposals (see [proposals/README.md](proposals/README.md)).                                    |
+| `docs/`                                       | Versioning, release, linking (ID/IDREF), gbXML, developer docs; Jupyter notebooks in `docs/notebooks`. |
+| `migration_scripts/`                          | `upgrade_from_X_to_Y.py` scripts for breaking upgrades between adjacent versions.                      |
+| `spec/validation_spec.rb`                     | RSpec checks run by `bundle exec rake`.                                                                |
+| `src/data_dictionary.rb`, `src/change_log.rb` | Data dictionary and changelog generators.                                                              |
+| `.github/instructions/`                       | File-scoped rules; read before editing matching files (see below).                                     |
+| `tmp/`                                        | Git-ignored scratch space. Never commit it.                                                            |
+
+## File-scoped rules (read before editing)
+
+- `BuildingSync.xsd`: [.github/instructions/schema-xsd.instructions.md](.github/instructions/schema-xsd.instructions.md)
+- `proposals/**/*.md`: [.github/instructions/proposals.instructions.md](.github/instructions/proposals.instructions.md)
+
+## Commands
+
+- Tests (CI): `bundle exec rake` then `bundle exec rake generate_data_dictionary` (the latter also detects name conflicts).
+- Format XSD/examples (removes tabs and XMLSpy comments, 2-space indent): `bundle exec rake remove_tabs`.
+- Lint/format everything else: `poetry run pre-commit run --all-files` (prettier for Markdown/YAML/JSON, ruff for Python with line length 140, trailing whitespace, end-of-file newline, JSON pretty-format).
+- Bulk documentation edits: `bundle exec rake generate_documentation_csv`, edit `updated_documentation` column, then `bundle exec rake update_documentation`.
+- On Windows, `C:\Ruby32-x64\bin\ruby.exe -S bundle exec rake` is more reliable than bare `bundle`.
+
+## Rules enforced by tests (`spec/validation_spec.rb`)
+
+1. Every `examples/*.xml` (except `*Invalid Schema*`) validates against `BuildingSync.xsd`.
+2. No tab characters in `BuildingSync.xsd` or `examples/*.xml`.
+3. No `XMLSpy` text in `BuildingSync.xsd` or `examples/*.xml`.
+4. No `xs:complexContent` anywhere in `BuildingSync.xsd`.
+5. Global `xs:element`/`xs:complexType`/`xs:simpleType`/`xs:attribute` names must not collide with gbXML global names (only `Capacity Latitude Location Longitude Manufacturer State ZipCode` are permitted).
+6. Named `xs:element` names must be unique across the whole schema, except the legacy `ignored_dupes` list. Never add to that list; reuse a shared type or `ref` instead.
+
+## Versioning and change classification ([docs/versioning.md](docs/versioning.md))
+
+Classify every schema change before making it and report the classification:
+
+- **Breaking (MAJOR)**: any historical document could stop validating - adding a required element/attribute, moving/renaming an element (including order in a sequence or new parent), changing to an incompatible type (e.g. decimal to integer), narrowing a simple-type restriction (removing an enum, tighter bounds).
+- **Non-breaking (MINOR)**: new optional element/attribute, compatible type widening (e.g. decimal to string), new enum value.
+- **Patch**: documentation-only changes, or restructuring that does not change what validates (e.g. inline definition to named type or `ref`).
+
+Deprecation policy (in the XSD header): **"Schema elements may only be removed by incrementing the major version of the schema document."** In a minor/patch release, deprecate instead of removing or renaming. Breaking changes need a migration script in `migration_scripts/` (see [upgrade_from_2.4_to_2.5.py](migration_scripts/upgrade_from_2.4_to_2.5.py)) that updates the root `version` and inserts a generated-from comment.
+
+## Workflow for a schema change
+
+1. Non-trivial features start with a proposal in `proposals/<current year>/<Title Case Name>.md` containing at least **Overview**, **Justification**, **Implementation** (breaking changes must discuss severity); optional **References**.
+2. Edit `BuildingSync.xsd` following [.github/instructions/schema-xsd.instructions.md](.github/instructions/schema-xsd.instructions.md).
+3. Update or add `examples/*.xml` when the change affects them; keep examples free of deprecated elements where possible.
+4. If a linking (`IDref`) element is added, update [docs/linking_elements.md](docs/linking_elements.md).
+5. Run `bundle exec rake remove_tabs`, `bundle exec rake`, `bundle exec rake generate_data_dictionary`, and pre-commit.
+6. Do **not** edit `CHANGELOG.md` or schema version numbers in feature PRs; the changelog is generated from PR labels at release time ([docs/release_instructions.md](docs/release_instructions.md)).
+
+## Pull requests ([docs/developer_resources.md](docs/developer_resources.md), `.github/workflows/CI_Labels.yml`)
+
+- One logical/discrete change per PR (e.g. removing an element is separate from adding an unrelated enum).
+- Use [.github/PULL_REQUEST_TEMPLATE.md](.github/PULL_REQUEST_TEMPLATE.md): background, what it does, how to test, relevant tickets, screenshots.
+- Labels (CI-enforced on `develop-v2`/`develop-v3`): either exactly one of `Breaking Change` / `Non-breaking Change` **plus** a `Schema: ...` scope label (`Controls`, `Documentation`, `General`, `Measures`, `Reports`, `Systems`, `Validation`), or `No Schema Changes` alone, or `ignore` alone (release/procedural PRs).
+- Contributions align with the release schedule: two releases per year (about end of May and November), cutoff about two weeks before ([.github/CONTRIBUTING.md](.github/CONTRIBUTING.md)).
+
+## Agent behavior
+
+- Read the relevant XSD region before editing; cite line numbers; never reformat unrelated parts of the 17k-line XSD.
+- Prefer additive, non-breaking changes; flag anything breaking and ask before proceeding.
+- Do not push, tag, release, or comment on GitHub issues/PRs without explicit approval.
+- Do not add files to the repo root or create summary markdown files unless asked; use `tmp/` for scratch notes.
+- Keep this file the single source of truth; update it (not the pointer files) when rules change.

BuildingSync.xsd

@@ -259,7 +259,7 @@
                                           <xs:documentation>Details about the the assessment. This might include methods used, criteria, evidence, or basis of evaluation.</xs:documentation>
                                         </xs:annotation>
                                       </xs:element>
-                                      <xs:element name="Tightness" type="auc:Tightness" minOccurs="0">
+                                      <xs:element name="Tightness" type="auc:TightnessType" minOccurs="0">
                                         <xs:annotation>
                                           <xs:documentation>Description of the infiltration characteristics for an opaque surface, fenestration unit, a thermal zone.</xs:documentation>
                                         </xs:annotation>
@@ -10677,7 +10677,7 @@
           <xs:documentation>True if fenestration is weatherstripped, false otherwise.</xs:documentation>
         </xs:annotation>
       </xs:element>
-      <xs:element name="TightnessFitCondition" type="auc:Tightness" minOccurs="0">
+      <xs:element name="TightnessFitCondition" type="auc:TightnessType" minOccurs="0">
         <xs:annotation>
           <xs:documentation>Indicator of expected air leakage through fenestration.</xs:documentation>
         </xs:annotation>
@@ -15598,7 +15598,7 @@
       <xs:enumeration value="Unknown"/>
     </xs:restriction>
   </xs:simpleType>
-  <xs:simpleType name="Tightness">
+  <xs:simpleType name="TightnessType">
     <xs:restriction base="xs:string">
       <xs:enumeration value="Very Tight"/>
       <xs:enumeration value="Tight"/>