Migration from legacy packs

This project is meant to replace legacy .pck or EterPack-style content delivery gradually, not through a single risky cutover.

Target state

Linux builds produce .m2p
the client loads .m2p first
runtime master key delivery is required
silent fallback to legacy packs is disabled in production

Suggested migration phases

Phase 1: parallel loader

keep the legacy loader in the client
add .m2p support beside it
verify the new loader against real content sets
keep fallback only in development if needed

Phase 2: pipeline validation

build .m2p from the same source tree as legacy packs
run verify for every archive
run diff between the source tree and .m2p
compare in-game behavior between legacy and .m2p

Phase 3: runtime delivery

stop embedding a real content key in the client
deliver the runtime key through launcher, environment, or mapping
verify startup failure behavior when the runtime key is missing

Phase 4: production cutover

package only .m2p for release clients
disable silent fallback to legacy packs
remove stale pack generation from release CI
keep extract/debug tools only for internal use

Recommended checks

duplicate normalized paths
invalid relative paths
case-collision problems on Windows
decompression failures
manifest signature failures
key mismatch by key_id

Practical migration loop

Pick one legacy pack group.
Rebuild it as .m2p.
Verify it.
Diff it against the source tree.
Boot the client with runtime keys.
Validate asset loads in logs and in-game.
Move to the next pack group.

Confirmed startup-safe pack group

The following startup pack set has already been validated against the real client runtime on the Linux VPS:

root
patch1
patch2
season3_eu
metin2_patch_snow
metin2_patch_snow_dungeon
metin2_patch_etc_costume1
metin2_patch_pet1
metin2_patch_pet2
metin2_patch_ramadan_costume
metin2_patch_flame
metin2_patch_flame_dungeon
locale
uiscript
uiloading
ETC
item
effect
icon
property
terrain
tree
zone
outdoora1
outdoora2
outdoorb1
outdoorc1
outdoorsnow1
pc
pc2
guild
npc
monster2
sound
sound_m
sound2

Validation method:

build each pack as .m2p
remove the matching legacy .pck
provide the runtime master key through:
- M2PACK_MASTER_KEY_HEX
- M2PACK_KEY_ID=1
start the Linux-built Windows client with xvfb-run + wine

Observed result:

PackInitialize succeeded
Python startup succeeded
app.Create(...) succeeded
client reached MainStream.SetLoginPhase()

For the world, audio, and gameplay-adjacent packs in this list, the current validation level is startup regression smoke only. Full confidence for those packs still requires map-load or in-game coverage.

Recommended next pack groups:

remaining startup-adjacent patch packs
remaining late-load gameplay content not covered yet
scenario-based validation for world, actor, and sound packs

Risk notes

Do not mix silent fallback with production security claims.
Do not ship a client that accepts .m2p without runtime key enforcement.
Do not keep real secret keys inside the repository.

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