Feat/runner array length#476
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The discriminating oracle for the array `.length` read slice, authored BEFORE the impl so the runner change is built to this spec. RED-at-base: the certify cases abstain today (the `member` case admits only a caught-error `.message`); they turn green only when the runner reads array length. The fences already pass (abstaining is the correct fail-close at base). - packages/core/tests/runner-array-length.test.ts (new) — direct ReferenceRunner spec: 6 certify cases (count / empty-0 / nested TOP-LEVEL count / arithmetic flow / scalar bind / parenthesized receiver) + 14 fail-close fences (string, ASTRAL string, number, boolean, rebound, array-literal receiver, index-position receiver, chained member, non-`length` member, optional, computed, unbound, and two direct evalPortableValue checks). - packages/python/tests/kern-run-cli-differential.test.ts — 4 `.length` CERT entries (count / empty / nested top-count / arithmetic), every byte verified on real node + python3 via the emitter probe. - packages/cli/tests/run.test.ts — CLI exit-code contract: `.length` happy (count / empty / arithmetic, exit 0) + abstain (string / astral / optional / computed / non-`length` member, exit 2). Module doc updated. Only ARRAY `.length` certifies: a STRING receiver abstains because JS `.length` counts UTF-16 code units while Python `len()` counts code points — `"😀".length` is 2 in JS, 1 in Python (verified). Reference-only — the emitters already lower a portable array `.length` to `len(...)` (Python) / `.length` (TS). ⚔️ Forged by [Agon](https://github.com/KERNlang/agon) Co-Authored-By: agon (KERN) <292465531+KERN-Agon@users.noreply.github.com>
The ReferenceRunner — the executor `kern run` uses — now READS an array's
ELEMENT COUNT, so a program can ask how big an array is natively:
let xs = [1,2,3] -> print xs.length -> 3
This continues the array slices (2a literal binding + each, 2b literal index).
An array branch is added to the `member` case of `evalPortableValue`, BEFORE the
caught-error `.message` handling and behind the SAME fences: a `.length` read
certifies ONLY as a non-optional `.length` on a BARE IDENTIFIER bound to a
portable array, and returns the element count — a non-negative safe integer.
Everything else throws -> the runner ABSTAINS.
Only ARRAYS certify. A STRING `.length` must NOT: JS `.length` counts UTF-16
code units while Python `len()` counts code points, so `"😀".length` is 2 in JS
and 1 in Python (verified on real node + python3). `Array.isArray` excludes
strings, numbers, booleans, decimals, and caught errors, so every non-array
receiver falls through and abstains. Non-ident receivers (`[1,2,3].length`,
`xs[0].length`, `xs.length.foo`), optional (`xs?.length`), computed
(`xs['length']`), a non-`length` member (`xs.foo`), rebound, and unbound idents
all abstain too.
Reference-only change: an abstaining program is never certified and never
reaches the emitter differential. The emitters ALREADY lower a portable array
`.length` to `len(...)` (Python) / `.length` (TS), so no codegen change is
needed; the 3-leg differential passes as-authored. The length value is an
ordinary safe integer, so it flows through arithmetic / comparison / binding /
print with no further hazard. `evalPortableValue` is internal to the
ir/semantics runner layer (not re-exported), so `.length` extends only the
runner's scalar contexts (print / if / while / fmt / assign), consistently
fenced.
The slice-2a `.length access abstains (deferred)` fence is updated to assert a
STRING `.length` abstains (array `.length` now certifies) — mirroring how
slice-2b relaxed slice-2a's in-bounds index fence.
Gate: array-length spec 20/20 + array-values 13/13 + array-index 25/25 +
runner-entry-import-graph + ir-semantics neighborhood 164/164 + CLI run.test
52/52 + 3-leg differential 23/23 (0 skipped) + biome + docs:contracts:check.
Planned with agon brainstorm; built by codex via agon conquer against the
RED-at-base oracle; reviewed by the full agon roster.
⚔️ Forged by [Agon](https://github.com/KERNlang/agon)
Co-Authored-By: agon (KERN) <292465531+KERN-Agon@users.noreply.github.com>
…fence coverage
Full-roster agon review (4 engines clean; kimi 2 important + nits). Triaged:
- [important 0.90] Member case lacked a hasBinding check (unlike the sibling
index case), so an UNBOUND receiver failed with the generic "outside portable
scalar domain" instead of a precise "binding not found". Still abstained either
way — diagnostics, not soundness — but now consistent with the index case.
- [important 0.60] Parenthesized-receiver test "may not match parser" — REFUTED:
`parseExpression("(xs).length")` yields a member on a bare ident (verified) and
the test is green; it documents real, sound certifying behavior. Kept.
- nits adopted: NULL and DECIMAL (tagged-object) receiver fences added, a
nested-array TOP-LEVEL-count CLI happy test added, and the direct-helper test
renamed from "abstains" to "throws" (abstain is runner-level terminology).
Gate: array-length 24/24 + array-values 13/13 + array-index 25/25 + CLI 53/53 +
biome. No behavior change to certified output; abstain outcomes unchanged.
⚔️ Forged by [Agon](https://github.com/KERNlang/agon)
Co-Authored-By: agon (KERN) <292465531+KERN-Agon@users.noreply.github.com>
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tsc -bpassespnpm testpassespnpm test:kernpassespnpm lintpasseskern review packages/ --recursivechecked