drukscode-v2/docs/developer/export-pipeline.md

Export Pipeline

The export pipeline turns a WebApp model into a signed APK. It lives in app/src/main/java/br/com/drukstech/codeapp/core/apkbuilder/ (~24 files).

Key classes

File	Role
ApkBuilder.kt	Orchestrates APK assembly + signing. Contains WebApp.toApkConfig(...).
ApkConfig.kt	The master config schema: data class ApkConfig(meta, activation, adBlock, webView, proxy, dns, nodejs, phpApp, pythonApp, goApp, multiWeb, ...). Everything an exported APK can encode.
ApkConfigJsonFactory.kt	Serializes ApkConfig to the assets JSON the shell reads; includes ApkConfigValidator.
ApkTemplate.kt / ShellTemplateProvider.kt	Locate and load the shell template APK.
ApkBuildCache.kt	Incremental rebuild; defines enum class IncrementalBuildMode (ModifyApkMode only covers FULL/CONTENT_OVERLAY).
AxmlEditor / AxmlRebuilder	Edit/rebuild the binary AndroidManifest (AXML).
ArscEditor / ArscRebuilder	Edit/rebuild the binary resource table (resources.arsc).
JarSigner.kt	Signs the APK with the com.android.apksig library directly (ApkSigner, V1/V2/V3 toggles).
ZipAligner / ZipUtils	Zip alignment and low-level zip manipulation.
ElfAligner16k.kt	16KB-page ELF alignment for native .so files.
RuntimeAssetEmbedder.kt	Injects runtime assets (Node/PHP/Python/Go) into the APK.
NetworkSecurityConfigBuilder.kt	Generates the network security config XML.

Related: core/playstore/aab/ handles AAB/Play packaging; core/crypto/ (AssetEncryptor, EncryptedApkBuilder, KeyManager) handles asset encryption.

The flow

WebApp (editor model)
  → WebApp.toApkConfig()          [ApkBuilder.kt]
  → ApkConfig                     [typed schema, *Block sub-objects]
  → ApkConfigJsonFactory          [serialize to app_config.json]
  → embed into template assets
  → patch AXML / ARSC (identity, permissions, icon)
  → embed runtime assets (if a server runtime)
  → sign (V1/V2/V3)
  → output APK

ApkConfig structure

ApkConfig is composed of a MetaBlock plus dozens of feature blocks (WebViewBlock, ProxyBlock, DnsBlock, NodejsBlock, PhpAppBlock, PythonAppBlock, GoAppBlock, MultiWebBlock, AdBlockBlock, …). Convenience getters on ApkConfig flatten these (appName, targetUrl, adBlockEnabled, …).

The JSON field names produced by ApkConfigJsonFactory must match the @SerializedName annotations in the shell config class — see Config Field Drift.

Incremental rebuild (ApkBuildCache)

Three modes (enum class IncrementalBuildMode):

Mode	Meaning
FULL	Rebuild from template. Always used for encrypted builds.
CONTENT_OVERLAY	Only app content changed; overlay onto a prior build.
REUSE_UNSIGNED	Re-sign a previously built unsigned APK.

Rules:

• Cache keys are content-stable hashes — never mtime-based.
• Template / entry identities must be content-stable.
• Encrypted builds always force a full rebuild.
• Do not feed signed or renamed APKs back into full modifyApk as templates.

Native library embedding

• Node.js export must embed libnode_bridge.so + libnode.so (16KB-aligned via ElfAligner16k) + libc++_shared.so.
• Go export must embed libgo_exec_loader.so.

Missing any native lib causes loadNode / loadJniBridge failure at runtime.