gen1recomp/docs/switch-development.md

Nintendo Switch development (love-nx)

Gen1Recomp on Nintendo Switch runs on a pinned love-nx runtime. This document covers vendor layout, fetch instructions, and the Mac ↔ Switch transfer workflow.

love-nx 11.5-nx1 (pinned)

Tag: 11.5-nx1

Local layout (not committed):

.bazinga/love-nx/11.5-nx1/
├── love.nro    # homebrew launcher binary (loose mode: copied to gen1recomp.nro)
└── love.elf    # required for fused NRO builds (devkitPro nacptool/elf2nro)

Manifest: scripts/switch/love-nx-11.5-nx1.sha256 lists expected artifact names and SHA-256 checksums. Checksums are filled when binaries are fetched (TBD_* placeholders until then).

Fetch instructions

1. Open the 11.5-nx1 release and download love.nro and love.elf.

2. Create the directory: mkdir -p .bazinga/love-nx/11.5-nx1

3. Move both files into that directory.

4. Record checksums and update the manifest:

   shasum -a 256 .bazinga/love-nx/11.5-nx1/love.nro \
     .bazinga/love-nx/11.5-nx1/love.elf
   

5. Replace the TBD_* lines in scripts/switch/love-nx-11.5-nx1.sha256 with the real hashes.

Never commit love-nx binaries, ROM dumps, or generated cache into git. The repo .gitignore excludes .bazinga/ (vendor cache) and /dist/ (build output).

Loose-mode dist layout

Development builds place gen1recomp.nro and game.love side by side:

dist/switch/loose/
├── gen1recomp.nro
└── game.love

Assemble with:

scripts/build_switch.sh --loose

(See scripts/switch/assemble_loose.sh for the underlying copy + checksum step.)

Transfer policy (mandatory)

Mac ↔ Switch file movement uses USB/MTP only:

• Switch: DBI → Run MTP responder
• Mac: OpenMTP (Apple Silicon build)
• Destination root: 1: SD Card/switch/gen1recomp/

Forbidden for this project (do not use as workarounds):

• Removing the microSD card to mount it on the Mac (/Volumes/…, Finder copy)
• FTP / Sphaira / any network file share to the Switch
• nxlink / netloader deploy
• DBI MicroSD install, NAND install, or other virtual install folders (NSP/NSZ/XCI paths)

If MTP fails, diagnose cable, USB port, DBI state, and OpenMTP exclusivity — do not silently fall back to forbidden methods.

OpenMTP + DBI transfer (loose build)

On the Switch

1. Close Gen1Recomp if it is running.
2. Open DBI from hbmenu.
3. Select Run MTP responder (DBI documents X on the main screen).
4. Keep DBI on that screen for the entire transfer.
5. Connect the Switch to the Mac with a USB-C data cable.

On the Mac

1. Close any other MTP clients.

2. Open OpenMTP and select the DBI device.

3. In the remote pane, open 1: SD Card.

4. Navigate to switch/ and create gen1recomp/ if needed.

5. Enter 1: SD Card/switch/gen1recomp/.

6. Drag from the local pane:

   dist/switch/loose/gen1recomp.nro
   dist/switch/loose/game.love
   

7. Wait for the OpenMTP queue to finish completely.

8. Refresh the remote listing and confirm file sizes match the local files.

9. On the Switch, exit MTP responder normally in DBI before launching the app.

Expected layout on SD:

1: SD Card/
└── switch/
    └── gen1recomp/
        ├── gen1recomp.nro
        └── game.love

Round-trip SHA-256 verification

For the first deploy of each artifact type (loose pair, later fused NRO), verify MTP integrity:

1. Before send — record local hashes:

   shasum -a 256 dist/switch/loose/gen1recomp.nro \
     dist/switch/loose/game.love
   

2. After send — in OpenMTP, copy the same files from 1: SD Card/switch/gen1recomp/ back to an empty local folder, e.g. dist/switch/mtp-roundtrip/.

3. Compare round-trip hashes:

   shasum -a 256 dist/switch/mtp-roundtrip/gen1recomp.nro \
     dist/switch/mtp-roundtrip/game.love
   

4. Local pre-send and round-trip hashes must match. Record results in the test report template below.

Repeat whenever a cable glitch or interrupted transfer is suspected.

Title override launch (full memory)

Applet Mode is not the primary validation path. Use title override so hbmenu runs with full memory:

1. Confirm the OpenMTP transfer queue finished.
2. Exit MTP responder in DBI; disconnect USB if desired.
3. Hold R while launching any legitimately installed title.
4. Keep holding until hbmenu appears.
5. Confirm hbmenu does not show Applet Mode.
6. Launch gen1recomp (or the probe NRO during Phase 0).

Album / applet launches are only useful to document applet-specific limitations; P0/P1 gates use title override.

Phase 0 hardware checklist

Complete in order on OLED hardware. Operator fills evidence fields — leave blank until tested.

Step	Action	Pass	Evidence / notes
P0-0a	Fetch love-nx 11.5-nx1; record manifest SHA-256	yes	See scripts/switch/love-nx-11.5-nx1.sha256
P0-0b	Build switch-probe.love per tools/switch-probe/README.md	yes
P0-0c	Assemble loose probe (game.love = probe) to dist/switch/loose/	yes
P0-0d	MTP deploy to 1: SD Card/switch/gen1recomp/; round-trip SHA-256	yes	nro 8290ac15…5918f5; love 9f198637…fa2e34f
P0-0e	Title override → probe boots; getOS() shows NX	yes	getOS()=NX, love._os=NX
P0-0f	Probe lists 1280×720 (or documented dims), save path, gamepad/touch log	yes	save sdmc:/switch/gen1recomp/switch-probe; Joy-Con Y→#3 X→#4
P0-1a	Replace game.love with unpatched Gen1Recomp build	yes	feat/switch-nx inbox build
P0-1b	MTP replace game.love only; round-trip SHA-256	yes
P0-1c	Title override → launcher reaches import screen	yes
P0-1d	Joy-Con: can navigate launcher (no touch-only)	yes	Full report: docs/switch-hardware-evidence.md

Operator: Andrew Date: 2026-08-01 Console: Switch OLED
love-nx tag: 11.5-nx1 gen1recomp commit: df7cea4

Phase 0 test report template

Copy this block into your hardware notes or PR evidence. Do not commit ROM files or ROM hashes of private dumps.

## Switch Phase 0 — hardware report

- Operator:
- Date:
- Console model:
- Atmosphère / HOS version:
- gen1recomp commit:
- love-nx tag: 11.5-nx1
- love.nro SHA-256 (local):
- game.love SHA-256 (local, pre-send):
- MTP round-trip SHA-256 (gen1recomp.nro):
- MTP round-trip SHA-256 (game.love):
- Title override used: yes / no
- Applet Mode observed: yes / no (should be no for P0)
- Probe getOS():
- Probe dimensions:
- Probe save directory shown:
- Gamepad events logged: yes / no
- Touch events logged: yes / no
- Unpatched launcher boot: pass / fail
- Joy-Con launcher navigation: pass / fail / not tested
- Notes:

Fast dev loop (loose mode)

While iterating on Lua/assets:

1. Edit on Mac; run scripts/test.sh --quick.
2. Rebuild .bazinga/work/game.love (scripts/build.sh mac --no-notarize or project pack step).
3. Close Gen1Recomp on Switch.
4. DBI → Run MTP responder.
5. OpenMTP → 1: SD Card/switch/gen1recomp/.
6. Replace only game.love; wait for queue + refresh listing.
7. Exit MTP responder; launch via title override.
8. Keep gen1recomp.nro unchanged until the love-nx pin changes.

scripts/test.sh --quick
scripts/build.sh mac --no-notarize
scripts/build_switch.sh --loose
shasum -a 256 .bazinga/work/game.love

Controller input mapping (NX)

Measured on Switch OLED (feat/switch-nx, love-nx 11.5-nx1, 1280×720). Both joystickpressed and gamepadpressed fire for Joy-Con; prefer the gamepad path when joystick:isGamepad() is true.

Path	Control	Mapping
gamepadpressed	D-pad / left stick	move
gamepadpressed	SDL a / b on NX	swapped via NX_GAMEPAD_BINDINGS: physical A (east) = GB A confirm, physical B (south) = GB B cancel
gamepadpressed	SDL a / b on desktop	identity (SDL south = GB A)
gamepadpressed	start / back	Start / Select
joystickpressed (raw)	only if not isGamepad()	face/menu fallback
joystickpressed (raw)	#1 / #2 on NX	Nintendo B / A → GB B / A
joystickpressed (raw)	#9 / #10	Select / Start (− / +)

Nintendo UX on Switch: physical A confirms, physical B cancels (explicit NX remap of SDL face labels).

Dual-path rule: love-nx emits both gamepadpressed and joystickpressed for Joy-Con. When joystick:isGamepad() is true, Input and RomImporter ignore raw face/menu so NamingScreen does not see A+B in one frame. NamingScreen also prefers A over B if both edges still fire.

Implementation: src/core/GamepadMap.lua (NX_RAW_*, ignoreRawForJoystick). Launcher and gameplay share the same converter.

Opt-in diagnostics: create an empty switch-debug.txt in the save directory; events flush to switch.log at ≤1 Hz with build identity (no ROM/save bytes).

Hardware re-test: T16 pass @ 2699c9a (naming A=confirm / B=cancel). T19 pass (quit/reopen, suspend×10, reboot) — operator 2026-08-01.

Suspend/resume audio: after resume, chip music is stopped to avoid duplicate streams; confirm on hardware during P0-09/10 (T19).

Lua error log (save directory)

On any uncaught Lua error, Gen1Recomp appends a redacted trace to lua-error.log in the LÖVE save directory (love.filesystem.getSaveDirectory()). The on-screen error overlay includes a hint pointing at that file. Logs rotate to lua-error.log.1 when the active file exceeds 32 KiB. ROM/save bytes and non-printable data are stripped — never commit or share logs that might contain private paths without reviewing them first.

Native crash triage (love-nx / Atmosphère)

love-nx native faults land under the console’s crash_reports/ folder on SD (reachable via the same MTP workflow as game deploys).

1. Collect — DBI → Run MTP responder; copy sdmc:/crash_reports/*.bin (or the dated subfolder) to the Mac. Do not remove the microSD card.

2. Redact — delete any attached screenshots or notes that mention ROM filenames, save paths, or private hashes before sharing logs publicly.

3. Symbolize — use the pinned love.elf from .bazinga/love-nx/11.5-nx1/ that matches build-info.json / scripts/switch/love-nx-11.5-nx1.sha256. Never use a “latest” download.

   # Example: aarch64-none-elf-addr2line from devkitPro
   aarch64-none-elf-addr2line -e .bazinga/love-nx/11.5-nx1/love.elf -f -C 0xADDRESS_FROM_CRASH_REPORT
   

4. Correlate — compare gitCommit / loveNxTag from embedded build-info.json with the operator’s hardware notes.

If addr2line cannot resolve an address, archive the crash .bin with the exact love.elf SHA-256 used for the build — addresses are only meaningful against that ELF.

P0 / P1 hardware matrix (ADR §9)

Operator evidence lives in docs/switch-hardware-evidence.md. Do not invent passes for rows that require hardware not yet run.

ID	Requirement	Status	Evidence
P0-0a–f	love-nx pin, probe, MTP, title override	pass	Phase 0 checklist above; T4
P0-1a–d	Unpatched launcher boot + Joy-Con nav	pass	T4 / docs/switch-hardware-evidence.md
P0-02	MTP inbox import path shown	pass	T12
P0-03	Rescan imports ROM	pass	T12
P0-04	Canonical hash routes version	pass	T12
P0-05	Source dump retained in inbox	pass	T12
P0-06	Play reaches game after import	pass	T12
P0-07	Joy-Con launcher navigation	pass	T16 @ 2699c9a
P0-08	Joy-Con gameplay (incl. naming A/B)	pass	T16 @ 2699c9a
P0-09	Save survives quit + reopen	pass	T19
P0-10	≥10 suspend cycles, no stuck input/dup audio	pass	T19 (operator 2026-08-01)
P0-12	Fused NRO boots without adjacent game.love	pass	T24 — docs/switch-hardware-evidence.md
P0-14	Fused NRO MTP round-trip SHA-256	pass	T24 — first artifact b019e2e8… @ 6fb5602 (redeploy after Blue fix)
P0-15	Replace NRO only; saves persist	pass	T24 — operator NRO-only update keeps saves
P1-01	Docked vs handheld spot-check	deferred	Not exercised on OLED dock yet
P1-02	Applet Mode documented unsupported	pass	Title override required; Album path not validated
P1-03	Long-play soak (≥30 min)	deferred	No soak session recorded
P1-04	Reboot persistence	pass	T19
P1-05	Audio resume after suspend	pass	T19 (no dup audio reported)

Upstream contribution outline (ADR §11)

Split the eventual upstream PR into three reviewable slices. Each PR must declare: no ROM/save bytes committed, love-nx pin with manifest checksums, hardware-tested rows listed, Applet Mode unsupported, network/updater disabled on NX.

PR 1 — Platform + import (platform/import)

• src/core/Platform.lua, conf.lua NX branch
• src/import/RomImporter.lua (NX flags, inbox, scan, shell/updater gates)
• Tests: tests/platform_nx_*, tests/rom_importer_nx_*
• Docs: inbox/MTP import sections only

PR 2 — Input + lifecycle (input/lifecycle)

• src/core/GamepadMap.lua, Input.lua, main.lua focus/joystick hooks
• src/debug/SwitchDiagnostics.lua (opt-in probe + error log)
• Tests: input/diagnostics suites
• Docs: controller mapping, suspend/audio notes

PR 3 — Build + docs (build/docs)

• scripts/pack_love.sh, scripts/build_switch.sh, scripts/switch/*
• assets/switch/icon.jpg, docs/switch-development.md, hardware evidence templates
• Gates: pack_love.sh --dry-run, verify_payload.sh --self-test, fused build script (devkitPro host)

Pre-merge checklist (all PRs):

• Manifest scripts/switch/love-nx-11.5-nx1.sha256 filled; binaries not in git
• verify_payload.sh rejects generated cache / ROM / .sav / .bak
• P0 matrix rows marked pass only with linked hardware evidence
• Fused NRO P0-12/14/15 pass with T24 evidence (docs/switch-hardware-evidence.md)
• Updater / remote mod download hidden on NX (networkValidated == false)