Invariants: The resolver

Who reads the resolver's answer and its vocabulary, where its installations are detected, and the RetroDECK folders taken from it. How an entry reads and binds, and the other areas: the register's index.

• The resolver's answer is read only in the adapter that asks for it — adapters/atlas_catalogue.py, atlas_firmware.py, atlas_launch.py, atlas_platforms.py, atlas_saves.py, emulator_sources.py and retrodeck_folders.py: only they import the resolver, and only names in atlas.__all__ — check + test + prompt-only

  Outside them no backend module and no panel code names one of the resolver's codes, a distinctive value of any other closed vocabulary it exports or one of its distinctive answer field names; and every caveat, health-issue, unresolved and reason code the vendored resolver states is classified by one of them or stands on the list of codes nothing classifies today. Only infrastructure and homonyms are excepted: by name, each with its reason, adapters/atlas_zstd.py imports the resolver to hand it the zstd codec and adapters/emulator_sources.py holds RealMachine (IMPORT_GRANTS, INTERNALS_GRANTED); tests/ is excepted as a whole, because tests build the resolver's machines and answers rather than read an answer for display; and a name that means something else in a module stands on NOT_THE_RESOLVERS, in the backend's check and in the panel's rule. The modules that read the answer today (READERS_TODAY, RESOLVER_READERS_TODAY), atlas_firmware.py's three private imports (INTERNALS_TO_REMOVE), the homonyms, the generic words left unwatched (GENERIC_VALUES, and in the panel alone PANEL_GENERIC_VALUES) and the codes nothing classifies (_UNCLASSIFIED) stand on lists that only shrink

  scripts/check_resolver_reading.py (the backend's imports and vocabulary, and that frontend/resolver-vocabulary.json is what it writes today; what it does not see is listed in its docstring), the ESLint rule tender/no-resolver-vocabulary in frontend/eslint.config.js, kept live by frontend/src/eslintNoResolverVocabulary.test.ts, and tests/adapters/test_resolver_codes.py (a code is classified once a reading module imports its constant). Every list but READING_MODULES, which is held to what was decided rather than to what reads, fails on an entry nothing needs any more — a generic word once Tender's own code no longer speaks it or the resolver no longer states it; the readers', internals', homonyms' and generic words' lists fail their tests on an entry they did not hold when they were written, and the reading modules and the two grants are held to exactly what was decided; the codes nothing classifies are the classification test's own list, which fails on a code a reading module classifies or the resolver no longer states, so a code added to it is an edit of that test. Unseen by the ESLint rule: a second site in a listed or excepted file reading the name it stands there for; a name as a plain string ("satisfied" in row, Pick<T, "satisfied">, T["satisfied"]); a code, value or name spelled as the name of a class field, a class method, a method in a type, an enum member, a JSX attribute or a binding (a variable, a parameter, a function, a class, a type, an import or an export), or as a qualified name in a type (typeof a.pal); test files, src/test-setup.ts and src/test-utils/; a code or name built at run time; a field reached through a spread or Object.entries; a generic word of those vocabularies, which the check leaves out (GENERIC_VALUES); a word the panel alone speaks with a meaning of its own, which the rule leaves out in the panel (PANEL_GENERIC_VALUES); a word of Tender's own spoken inside one of those vocabularies ("rejected"); and a watched value handed on through a parameter or a field of Tender's own name. Unseen by the classification test: whether a reading module that names a code reads it rightly. Prompt-only: an entry on NOT_THE_RESOLVERS is a name that means something else in its module, never a read of the resolver's answer; a code the resolver adds is classified by a reading module rather than added to the list; Tender keeps no table of its own for anything the resolver answers (find rules, launch command patterns, launch-file types, RomM regions); a join is on the resolver's keys (declared, (emulator, declared_index)), never on file_name alone or a label; where the resolver gives no answer, Tender says it could not be established and an emu-atlas issue asks for it; no decision is proposed that lets Tender work out a fact the resolver states — because the resolver is slow, cannot answer yet, or another page already does it; and the derivations and imports on today's lists stand until the issue that builds their kind's reading module removes them (#2579 D5): fixing one is not a finding, extending one or copying it to a new page is. Without the rule, every layer after the adapter decides a fact of its own from the raw answer, and the layers disagree: whether a file is required, whether a one-of group is met, whether a file is there, which file a requirement means (one image under two spellings became two rows), and what a caveat code means, copied into the backend and into the panel. The adapter turns the answer into Tender's own view, joined on the resolver's keys; the panel receives Tender's own closed set of marks per row, group and emulator and words them; and a Tender field that carries one of the watched names is renamed when the reading module of its kind is built (#2579 D1–D3). Which names and values are watched, and why the others are not, is WATCHED_NAMES and GENERIC_VALUES in the script, and for the panel alone PANEL_GENERIC_VALUES in frontend/eslint.config.js. The checks hold the reading half of ADR-0042's first decision; the rest of it stays prose, the prompt-only part above - The resolver's installations are detected in one place, adapters/emulator_sources.py, through the one RealMachine the process keeps; every other adapter asks it, and a game's questions go to the source domain/emulator_sources.py::answering_source names — test + prompt-only — tests/adapters/test_emulator_sources.py::TestOnlyTheHolderDetects (no other backend module imports detect, every_installation, RealMachine or an installation class from the resolver, star-imports it, imports the resolver's package as a module, or reads one of those names off it) and, for the last clause, tests/domain/test_emulator_sources.py::TestAnsweringSource::test_retrodeck_answers_even_when_another_source_is_first_in_the_order and test_retrodeck_answers_with_emudeck_first_in_the_order in each of the three adapters' tests — tests/adapters/test_atlas_catalogue.py::TestWhichSourceAnswers, tests/adapters/test_atlas_firmware.py::TestDegradation and tests/adapters/test_atlas_saves.py::TestWhichSourceAnswers. An adapter that detected on its own would pick its own source — the old "first detected" — and would build a fresh machine, so every save question would run its core's probe again. Unseen by the scan: a name reached through getattr or importlib. Prompt-only: no adapter keeps a handle or an answer past the reading it came through (a panel call's per question, a run's for the run) - Every RetroDECK folder Tender downloads into, removes from, bounds a removal by or reads for the move code is the resolver's answer, asked through adapters/retrodeck_folders.py — test + prompt-only

  No module reads RetroDECK's settings or builds such a folder from a root — except the move code, which joins bios and saves onto each old home a pending move left — and a root the resolver only assumed (assumed in its roots answer, domain/source_roots.py) or gives no path for is used for nothing, each root judged by its own provenance, also under a marker-* finding, and a system's folder going with its ROM root; where detecting the sources or the roots question raised, none of those folders is used — except that a download while RetroDECK is switched off says so, and a raise on a system's own ROM folder refuses only the presses that need that folder; a removal of a game's files is bounded by its system's own ROM folder, never by the ROM root

  tests/domain/test_source_roots.py (the rule) and tests/adapters/test_retrodeck_folders.py (the real resolver over tmp homes: every folder its answer, TestEachRootIsJudgedByItsProvenance over a settings file without paths, one key unset, a version alone unreadable, ES-DE's own default ROM folder and an assumed home that is missing, each marker-* finding refusing the BIOS, saves and move questions and not-set-up every question, TestWhereAQuestionToTheResolverRaises and TestWhereDetectingTheSourcesRaises refusing every question for a raise on the detection or the roots and only its own for a system's folder, and TestNoModuleReadsRetroDecksSettings over the code's string constants) and tests/contract/test_retrodeck_folders.py (under each finding, with a key unset, and where the detection or the roots could not be asked, no press downloads, deletes, cleans up or migrates in a folder that was not read, the cleanup is refused at its start for an assumed saves root, and a version alone unreadable refuses no press); the system-folder bound by tests/services/test_downloads.py::TestASystemFolderLinkedToAnotherDrive and the linked-folder and one-system cases of tests/contract/test_prune.py, with Uninstall all's one-system case in tests/contract/test_retrodeck_folders.py (test_where_one_system_s_folder_question_raises_uninstall_all_goes_on_for_every_other_system). A folder of Tender's own beside the resolver's is the drift this replaced: retrodeck.json read twice, a system's ROM folder built as <roms root>/<system> in five places while ES-DE may declare another, and a fallback to ~/retrodeck that pointed downloads, deletes and the move code at internal storage while RetroDECK lay on an SD card. A root the resolver only assumed is the same kind of guess — RetroDECK's usual layout, below the home where the settings name one and at ~/retrodeck where they do not — whatever finding stands beside it (a retrodeck.json without paths or with one key unset carries none), so using it would be that guess again, and the missing-root findings the resolver states for it name a folder nobody configured (#2294). The rules each question answers by are on Config source parsers. A save's folder and a firmware file's place take the other route, the save and firmware answers (adapters/atlas_saves.py, adapters/atlas_firmware.py), and this entry does not cover them: a save's place comes from the emulator's own settings rather than from retrodeck.json, so under the three marker-* findings a save still syncs where the emulator keeps it, and a place those settings did not name is the save-answer entry's to refuse. Unseen by the tests: a folder joined onto a root under another name, and a caller that puts the question to RetroDECK's handle itself. Prompt-only: a new caller that downloads into, removes from or bounds a removal by a RetroDECK folder asks RetroDeckFolders and raises the refusal it answers with