Incremental Cache Keys

GOWDK cache keys are deterministic compiler inputs, not runtime state. The cache model is split by phase so invalidation can stay local and reviewable.

Key Model

Each key is a stable hash over the fields that affect the next compiler phase:

• .gwdk source key: parsed source kind, package, declared identity, route, metadata declarations, imports, use declarations, block bodies, endpoints, component contracts, layout references, CSS/asset selections, and source file path. Parser errors use the raw file hash until the file parses again.
• Go ABI key: owning package import path, package name, exported handler/type names used by .gwdk, resolved signatures, relevant struct fields and tags, build tags, GOOS/GOARCH, and Go toolchain version. Function bodies are not ABI input unless generated output embeds the body through an inline Go block.
• Config/target key: normalized compiler config, selected modules, selected build target, output mode, enabled feature flags, and active addons that affect generated output.
• Toolchain key: Go version, GOOS/GOARCH, build tags, and compiler feature gates that can change package loading or generated code.
• IR key: stable gwdkir.Program records that downstream generators consume, excluding diagnostics ordering noise and runtime-only secrets.
• Output-plan key: generated route, asset, CSS, app, backend, WASM, and binary plans plus the generator version that owns their shape.
• Generated-file key: output path, content hash, cache policy, and the source output-plan record that produced it.

Runtime-only values do not invalidate static output. For example, CSRF secret values rotate at runtime and are not cache inputs unless the generated code shape or config field that enables CSRF changes.

Reverse Dependencies

Reverse dependencies answer "which pages must be regenerated when this input changes?" and are derived from IR plus parsed view references:

• Page source changes affect that page.
• Component source changes affect pages that call the component directly or through another component.
• Layout source changes affect pages that name the layout, including parent layout chains.
• CSS source changes affect CSS artifacts and pages that include the stylesheet.
• Backend binding ABI changes affect generated adapters and reports, not static page HTML unless a build/load function contributes build-time output.
• Config, target, addon, toolchain, added source, and removed source changes conservatively invalidate the whole selected build.

Dependencies stay attached to explicit source kinds. Avoid catch-all global cache state; a phase may cache local package inspection or output planning, but the invalidation edge must name the source kind and owner.

Implemented Slice

The current implementation keeps the existing content-hash input snapshot for gowdk dev, then adds reverse dependencies for incremental SPA rebuilds:

• changed page sources still render only those pages;
• changed component sources render pages that reference the component directly or transitively through another component;
• changed layout sources render pages that use the layout or a child layout that inherits from it;
• added, removed, config, generated app, binary, WASM, backend, and configured target changes still fall back to the full build path.

When --timings is enabled, incremental rebuilds write the same timing sidecar as normal builds and include counters for input changes, affected pages, component/layout/page changes, files written, and identical writes skipped.