ww package: reject non-function main declarations
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@@ -7771,6 +7771,181 @@ ordinary non-list `[no matches]` plus accounting pinned.
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No persisted-byte contract changed: build workdir format remains `18`, test
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workdir format remains `19`, and semantic storage format remains `3`.
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### 11.38 Implemented declared-`main` function-kind semantics
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A package whose **declared package name** is `main` now rejects every
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package-scope non-function declaration named `main`. `let`, `const`, `def`, and
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`type` forms receive `cannot declare main - must be func` from either compiler
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checker and are not installed in package scope. The rule is deliberately
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narrower than Go's complete source signature rule: WW retains its established
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C/Hare-style program-entry ABI, including supported argument- and
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result-bearing function declarations.
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#### Pinned Go evidence and fact classification
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The sole authority is official Go 1.26.5 at commit
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`c19862e5f8415b4f24b189d065ed739517c548ba`:
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- `types2.(*Checker).declarePkgObj` tests both identifier spelling `main` and
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`check.pkg.name == "main"`, emits `cannot declare main - must be func`, and
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returns without declaring the object
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([`cmd/compile/internal/types2/resolver.go`, lines 90–110](https://github.com/golang/go/blob/c19862e5f8415b4f24b189d065ed739517c548ba/src/cmd/compile/internal/types2/resolver.go#L90-L110)).
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The public checker implements the same condition and return
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([`go/types/resolver.go`, method `(*Checker).declarePkgObj`, lines 103–124](https://github.com/golang/go/blob/c19862e5f8415b4f24b189d065ed739517c548ba/src/go/types/resolver.go#L103-L124)).
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- Official type-checker testdata rejects constant, type, and variable
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declarations named `main` in package `main`
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([`internal/types/testdata/check/decls5.go`, lines 5–10](https://github.com/golang/go/blob/c19862e5f8415b4f24b189d065ed739517c548ba/src/internal/types/testdata/check/decls5.go#L5-L10)).
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The fixed-bug test also rejects `var main = func() {}`: a variable containing
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a function is still not a function declaration
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([`test/fixedbugs/issue21256.go`, lines 1–9](https://github.com/golang/go/blob/c19862e5f8415b4f24b189d065ed739517c548ba/test/fixedbugs/issue21256.go#L1-L9)).
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Those conditions, diagnostics, early returns, and testdata assertions are
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**behavior directly implemented or asserted by pinned Go**. That the semantic
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owner is package declaration checking; that a rejected object does not become
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the entry binding; and that declared package name rather than canonical path,
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path leaf, physical directory, or command selection owns the rule are
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**behavior derived from the pinned implementation**.
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Pinned Go separately requires a function `main` in package `main` to have no
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arguments or results
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([`cmd/compile/internal/types2/resolver.go`, method
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`(*Checker).collectObjects`, lines 416–444](https://github.com/golang/go/blob/c19862e5f8415b4f24b189d065ed739517c548ba/src/cmd/compile/internal/types2/resolver.go#L416-L444)),
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asserted by official `mainsig.go`
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([lines 7–13](https://github.com/golang/go/blob/c19862e5f8415b4f24b189d065ed739517c548ba/test/mainsig.go#L7-L13)).
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That is also **behavior directly implemented or asserted by pinned Go**, but it
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does not honestly apply to WW's source ABI. Both baseline WW stages accepted
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`fn main(x: i32) void` and `fn main() i32`, produced byte-identical
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executables, and ran them successfully; WW's own self-hosted command tools use
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`main(argc: i32, argv: **u8) i32`. Those observations are **directly measured
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WW behavior**. Preserving those function forms while applying the independent
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declaration-kind requirement is **behavior derived from the pinned
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implementation within WW's applicable model boundary**.
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#### Fresh four-axis audit and direct pre-fix measurements
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The bounded audit examined all four permanent axes before this package slice
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was selected:
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- **Go-like build:** pinned `(*ErrorReporter).errorUnresolved` gives missing
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`main.main` a dedicated error
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([`cmd/link/internal/ld/errors.go`, lines 29–67](https://github.com/golang/go/blob/c19862e5f8415b4f24b189d065ed739517c548ba/src/cmd/link/internal/ld/errors.go#L29-L67)),
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asserted by `TestUndefinedRelocErrors`
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([`cmd/link/internal/ld/ld_test.go`, lines 19–45](https://github.com/golang/go/blob/c19862e5f8415b4f24b189d065ed739517c548ba/src/cmd/link/internal/ld/ld_test.go#L19-L45))
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and official `testdata/issue10978/main.go` lines 5–27. Both WW stages
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rejected a selected `main` package with no entry, emitted empty stdout and
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the same 50 stderr bytes (SHA-256
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`9ed4d7684412c6d2e615041902072c81e9e09acb3970246d89a2c8bdddd2fcfa`),
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and published nothing. This applicable control was aligned.
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- **Go-like test:** pinned `isTestFunc` and `checkTestFunc` define and reject a
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wrong test function shape
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([`cmd/go/internal/load/test.go`, lines 555–579 and 775–787](https://github.com/golang/go/blob/c19862e5f8415b4f24b189d065ed739517c548ba/src/cmd/go/internal/load/test.go#L555-L579)),
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with the official wrong-signature script anchor at
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[`cmd/go/testdata/script/test_main.txt`, lines 11–13 and 30–40](https://github.com/golang/go/blob/c19862e5f8415b4f24b189d065ed739517c548ba/src/cmd/go/testdata/script/test_main.txt#L11-L13).
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Both WW stages rejected `@test fn bad(x: i32) void` before execution, emitted
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the same semantic diagnostic, no accounting, and final `FAIL\n` stdout
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(SHA-256
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`4f8e9e45f8a9e1843b81eaf3bdf52a6b778d415d23bf985774a9d34a43f69bd5`).
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This applicable control was aligned.
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- **Go-like package:** baseline Cstage accepted `let main`, `const main`, and
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`def main`, published mode-0755 executables, and those executables exited 139
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with empty output. The `let`/`const` executable SHA-256 was
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`edd3bad62be69701a373aa0567972bfb976690b0332b8c117891125254fc85b5`;
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the `def` executable SHA-256 was
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`9e56d6710395b287e18e85187eee86d846927c6f3ea91216858c6026f38ebdff`.
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Cstage `type main` and every WWstage non-function form instead reached the
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linker's missing-`main` failure. Neither stage emitted the pinned package
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diagnostic. Both stages accepted a directory command package containing
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`let main` plus a valid internal test, ran it, and reported package `ok` with
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byte-identical 178-byte stdout (SHA-256
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`a6e165fb558be62932e217ccd1d3175348f7490489bca8e9828872e28c01236f`).
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This was the selected difference.
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- **Go-like import:** pinned `unusedImports` and `errorUnusedPkg` reject a
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nonblank unused alias
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([`cmd/compile/internal/types2/resolver.go`, lines 706–740](https://github.com/golang/go/blob/c19862e5f8415b4f24b189d065ed739517c548ba/src/cmd/compile/internal/types2/resolver.go#L706-L740)),
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asserted by official `importdecl0a.go` lines 9–27. Both WW stages rejected
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unused `import spare audit.dep;`, emitted empty stdout, and reported
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`"audit.dep" imported as spare and not used`. This applicable control was
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aligned.
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The WW command results, output lengths, hashes, exit statuses, and runtime
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signals are **directly measured WW behavior**. The linked source and testdata
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facts are **behavior directly implemented or asserted by pinned Go**. Selecting
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the declaration-kind rule while excluding the incompatible function-signature
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rule is **behavior derived from the pinned implementation**.
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As an identity control, both stages built `package utility; export let main:
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i32 = 7` as byte-identical 924-byte archives (SHA-256
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`10382e7812229d73c4acefdf8988a13372b6eb7a2981559b3adade524ed5a929`).
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That is **directly measured WW behavior** and pins the required non-effect for
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non-`main` declared packages.
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#### Ownership, final behavior, and preserved boundaries
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`reject_nonfunction_main_decls` in `cmd/wcc/check.c` and its self-hosted twin
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`rejectnonfunctionmaindecls` in `selfhost/cmd/wcc/check.ww` are the semantic
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owners. They run after parsing but before qualified-use discovery and package
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name installation. Each walks selected top-level declarations, tests the
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declaration-carried `pkgname`, reports the pinned diagnostic, and removes only
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the rejected node from subsequent package-scope checking. This mirrors the
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pinned resolver's return-before-declare behavior. No driver mode, entry flag,
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canonical action key, directory classification, or linker-symbol heuristic is
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consulted.
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Direct post-fix calls to `w6c` and `w6c_ww` on the same invalid source now exit
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1 with empty stdout, no assembly output, and byte-identical 102-byte stderr
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(SHA-256
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`39001ed88e2ab8b7675fcc51b4b794cf8ebc2a803e1f05de45d7d0ba1cd98a38`)
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ending in `cannot declare main - must be func`. Directory builds of all four
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forms fail through `ww: w6c failed for ...`, never reach `w6a` or `w6l`, publish
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no output, and give byte-identical Cstage/WWstage diagnostics when the owned
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output path is the same. Directory tests emit only the command-owned final
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`FAIL\n` on stdout, report build failure on stderr, and emit no test body,
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accounting, or package `ok` result.
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Loading and Go-platform source eligibility are unchanged. Production and test
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source selection still determines which declarations reach the checker; an
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excluded source has no effect. Declared package name remains independent from
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canonical dotted identity, aliases, path leaf, filename, physical directory,
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requested root, output name, linker order, and artifact/storage locator. A
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dependency physically and canonically ending in `main` but declared `utility`
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continues to export `main`, bind through its declared qualifier, and produce
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stage-byte-identical `.unit.ww`, `.wwi`, assembly, object, archive, and command
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executable bytes. Valid `main(argc, argv) i32` and `main() i32` commands remain
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accepted and byte-identical between stages.
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Graph construction and action identities are unchanged for valid programs. An
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invalid selected command or command-test variant reaches its normal compiler
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action and fails there; assembler, archiver, linker, runtime, generated test
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execution, and publication do not become alternative semantic owners. An
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ordinary import of a declared-`main` package is still rejected earlier by the
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loader as `ww: package PATH is a program, not an importable package`, even when
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that command also contains the malformed declaration. This preserves import
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diagnostic precedence and the toolchain-owned external-test exception.
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Cold rejection creates no output or retained scratch. Warm rejection after a
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successful command preserves the complete committed owner unit, interface,
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assembly, object, archive, init unit/assembly/object, tool vouchers, workdir
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stamp, and public executable byte for byte. It installs no staged generation;
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exact source restoration reuses the committed action and reproduces the prior
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binary. There is no test-result cache and no new reuse key. Producer failure,
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rollback, existing-output preservation, concurrent action isolation,
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interruption, process cleanup, and transaction cleanup continue through their
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existing owners; the checker adds no process, descriptor, mutable global state,
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or cleanup path. No active `.new`, `.install`, `.wwtxn.*`, adjacent rejection
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scratch, test child, or capture survives the tested failure boundaries.
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The WW-native `nonfunction_main_declarations_reject` observer proves all four
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non-function kinds, exact direct-compiler stage parity, cold build rejection,
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directory-test nonexecution, declared-name/dotted-import/physical-leaf
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separation, supported entry ABI preservation, valid artifact-byte parity,
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command-import precedence, complete warm work/publication rollback, restored
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reuse, and residue absence. Existing interruption and concurrent-transaction
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observers remain the owners of those unchanged mechanisms; this declaration
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check introduces no independently interruptible or shared state.
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No valid persisted-byte contract changed. Build workdir format remains `18`,
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test workdir format remains `19`, and semantic storage format remains `3`.
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## 12. Candidate architectures and hard-gate decision
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Five candidates were developed as coherent systems, not as feature bins.
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