Tricu 2.0.0

Sorry for squashing all of this but 🤷

demos/viewContracts/README.md

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+# View Contract Demos
+
+These demos exercise the finalized View Contract stack in `lib/view.tri`:
+portable View Trees/checkable typed-program nodes, structural View flow checks,
+runtime guarded Views, checked-exec, source annotations, and module-boundary
+View metadata.
+
+## End-user guide
+
+Start here. `demos/viewContracts.tri` is written with normal source annotation
+sugar and reads as a short guide to View Contracts: motivating structural
+mismatches, explaining plain Views, noting why this is not a full static type
+system, and building a custom `NonEmptyList` guarded View.
+
+```bash
+tricu check demos/viewContracts.tri
+```
+
+Expected output:
+
+```text
+ok
+```
+
+## Complete explicit demo
+
+`demos/viewContracts/complete.tri` shows the same layer from the portable
+View Tree/checkable-program side. It uses explicit builders such as
+`typedValue`, `typedRequire`, and `typedApply`, and demonstrates contextual guard
+diagnostics, observation composition, reachability, and malformed guard output.
+
+```bash
+tricu eval demos/viewContracts/complete.tri -f decode
+```
+
+## Portable checker self-tests
+
+Runs the checker self-test suite carried as ordinary `tricu` code.
+
+```bash
+tricu eval demos/viewContracts/selfTests.tri -f decode
+```
+
+Expected output is a list of `"ok"` strings.
+
+## Diagnostic rendering
+
+Shows a strict-mode structural View failure rendered for humans.
+
+```bash
+tricu eval demos/viewContracts/diagnostic.tri -f decode
+```
+
+Expected output:
+
+```text
+"symbol 162 expected List Bool but got List String"
+```
+
+## Stdlib-shaped contracts
+
+Checks successful higher-order contracts shaped like common stdlib APIs.
+
+```bash
+tricu eval demos/viewContracts/stdlibContracts.tri -f decode
+```
+
+Expected output:
+
+```text
+["ok", "ok", "ok", "ok", "ok"]
+```
+
+These examples are structural View checks, not runtime guarded checks.
+
+## Frontend emission layer
+
+`frontendEmission/` documents the portable artifact shape a frontend can emit
+after parsing/elaboration. The `*.source.txt` files are pseudo-source; the
+matching `*.emitted.tri` files are explicit typed-program builder output.
+
+This layer is still instructive because it shows the exact bridge between source
+syntax and portable View Tree/checkable metadata.
+
+## Source syntax sugar
+
+The `sourceSyntax/` demos use ergonomic annotations and the `tricu check`
+frontend. The frontend lowers annotations to the same typed-program nodes used by
+the explicit demos above, then executes checked-exec so guarded annotations fail
+through the portable runner.
+
+Successful check:
+
+```bash
+tricu check demos/viewContracts/sourceSyntax/success.tri
+```
+
+Expected output:
+
+```text
+ok
+```
+
+Labeled diagnostic check:
+
+```bash
+tricu check demos/viewContracts/sourceSyntax/failure.tri
+```
+
+Expected first failing diagnostic:
+
+```text
+symbol 4 (x) expected Bool but got String
+```
+
+If the first definition is fixed or removed, the later application-result
+failure demonstrates callee-aware labels:
+
+```text
+symbol 3 (g application result) expected String but got Bool
+```
+
+## Module boundary layer
+
+`modules/` shows producer-checked module export Views flowing into a consumer
+check as module-boundary evidence. During auto-build, annotated exports are
+checked before the module manifest alias is published. Consumers then use the
+manifest's View Contract metadata as assumptions, while compatibility is still
+judged by `lib/view.tri`.
+
+```bash
+tricu check demos/viewContracts/modules/success.tri
+# ok
+
+tricu check demos/viewContracts/modules/failure.tri
+# symbol 3 (Util.toString application result) expected Bool but got String
+```