main.janet held ~45 lines of env-knob policy (open-mode / direct-link / optimize
/ shapes / whole-program gates) that couldn't be unit-tested without the CLI, and
two disk-image caches (api/init-cached, main/deps-image) each hand-built a
POSITIONAL "%q|%q|..." key that silently misaligned if a ctx-shaping knob was
added in only one place.
config.janet now owns:
ctx-shaping-env-vars the canonical list of env vars that shape the built ctx
ctx-cache-key a labeled key (name=value) over a prefix + every shaping
var, so adding a knob updates BOTH cache keys at once and
can't positionally alias two different builds
resolve-run-mode [open-mode? main-entry?] -> the ctx env knob map
main shrinks to: compute open-mode?/main-entry? from argv, call resolve-run-mode,
install the knobs. Both deps-image-path (main) and image-cache-path (api) build
their keys via ctx-cache-key. New test/unit/config-test.janet locks in the
run-mode cases and asserts every ctx-shaping env var participates in the key.
Scope: this is 4a + the 4b cache-key footgun fix. The optional 4b cleanup
(folding the load/save image dance + aot marshal helpers into one ctx_image
module) is left for a follow-up — it's lower value and higher blast radius.
No behavior change (cache keys now key on a superset of env vars, so at worst a
one-time cold rebuild). Gate green: conformance 355x3, clojure-test-suite 4718
pass (>= 4695 baseline), config-test, full jpm test exit 0.
