# AGENTS.md

This file is the quick-start map for agents working in this repository. Keep it
small and point to the live docs instead of duplicating the whole plan.

## Current Modernization Goal

PanoPainter is being incrementally modernized into independently testable C++23
components while preserving current behavior. OpenGL remains the working backend
until the renderer boundary is proven; Vulkan/Metal/WebGPU work waits behind that
boundary.

Read these first:

- `docs/modernization/roadmap.md` - live phase roadmap, recent results, and next
  work queue.
- `docs/modernization/debt.md` - required debt log. Every temporary adapter,
  retained legacy dependency, skipped platform, fallback, or shortcut needs an
  entry with validation and removal conditions.
- `docs/modernization/capability-map.md` - behavior that must be preserved.
- `docs/modernization/build-inventory.md` - current build/component inventory.
- `docs/adr/0001-modernization-boundaries.md` - component boundary decisions.

## Working Rules

- Work on `codex/modernization-cmake-foundation` unless the user says otherwise.
- Commit and push each verified successful progress slice.
- Prefer larger coherent slices over tiny checkpoints, but keep docs/debt updated
  with each slice.
- Do not revert user changes. Unrelated untracked notes, such as
  `docs/human-review-notes.md`, should be left alone unless explicitly requested.
- Use CMake as the source of truth. Legacy Visual Studio project files are not the
  modernization path.
- Use `apply_patch` for manual source/doc edits.

## Build And Test

Primary Windows configure/build:

```powershell
cmake --preset windows-msvc-default
cmake --build --preset windows-msvc-default --config Debug --target PanoPainter pano_cli
```

Focused fast validation:

```powershell
ctest --preset desktop-fast --build-config Debug --output-on-failure
```

Useful targeted pattern:

```powershell
ctest --preset desktop-fast --build-config Debug -R "pp_app_core|pano_cli_plan" --output-on-failure
```

If MSVC reports corrupt debug information or stale PDB/object errors, clean the
generated build tree target before judging source changes:

```powershell
cmake --build --preset windows-msvc-default --config Debug --target clean
```

## Code Navigation

Codex has a repo-specific skill named `panopainter-code-navigation`. Agents must
use it when necessary: follow this path before broad text search when a task is
about C++ symbol identity, symbol families, declarations/definitions, override
groups, or platform/backend boundaries. Use it when
following C++ symbols, finding symbol families with regular expressions, tracing
service/interface wiring, or checking platform/backend boundary usage.
Reach for `--name-regex`,
`--detail-regex`, or `--path-regex` when looking for generated-style name
families, override groups, command/service families, signatures, or
platform/backend path slices. Use normal `rg` for docs, build files, comments,
string literals, generated command names, or exact non-C++ text.

Prefer compiler-aware navigation when following C++ symbols across the legacy
flat source tree and extracted components:

```powershell
python scripts/dev/clangd_nav.py symbols --file src/app_core/brush_ui.h --name execute_brush
python scripts/dev/clangd_nav.py symbols --file src/app_core/brush_ui.h --name-regex "execute_.*preset"
python scripts/dev/clangd_nav.py symbols --file src/app_core/document_export.h --detail-regex "Export.*Plan"
python scripts/dev/clangd_nav.py definition --file src/node_panel_brush.cpp --line 511 --column 39
python scripts/dev/clangd_nav.py references --file src/app_core/brush_ui.h --line 783 --column 45 --path-regex "src[\\/]app_core"
python scripts/dev/clangd_nav.py self-test
```

The helper talks to `clangd` using an existing `compile_commands.json`. It
defaults to `out/build/windows-clangcl-asan` and then `out/build/android-arm64`;
pass `--compile-commands-dir` or set `PP_CLANGD_COMPILE_COMMANDS_DIR` when using
another Ninja build tree. Use `--name` and `--max-results` to keep output small.
Use `--name-regex` for regex filtering against `qualifiedName`,
`--detail-regex` for symbol detail/signature filtering, and `--path-regex` for
definition/declaration/implementation/reference location filtering. Regex
matching is case-insensitive by default, and `--no-ignore-case` makes it
case-sensitive. Run `python scripts/dev/clangd_nav.py self-test` or the
`panopainter_clangd_nav_regex_self_test` CTest before relying on regex behavior
after tool changes.
Treat symbol, hover, declaration, definition, and implementation lookups as the
reliable path. Reference lookups are riskier because a one-shot clangd process
may not have a complete project index; the helper refuses reference queries
unless callers pass `--background-index` for broader best-effort results or
`--allow-incomplete-references` for explicitly current-translation-unit-only
results. Do not use incomplete reference output as proof that a symbol has no
other users.

## Current Architecture Direction

The desired component split is documented in the roadmap. Current extracted or
in-progress boundaries include:

- `pp_foundation`
- `pp_assets`
- `pp_paint`
- `pp_document`
- `pp_renderer_api`
- `pp_renderer_gl`
- `pp_paint_renderer`
- `pp_app_core`
- `pp_panopainter_ui`
- `pp_platform_*`
- `panopainter_app`

Legacy UI/app code still exists and is being reduced through pure planners,
service interfaces, CLI automation, and CTest coverage. When moving behavior out
of a legacy node, preserve current behavior first, add focused tests, document
remaining shortcuts in `docs/modernization/debt.md`, then wire the live adapter.

## Legacy Context

PanoPainter started as a flat C++17 OpenGL panoramic painting app centered on
singletons such as `App::I`, `Canvas::I`, `Settings`, and `WacomTablet::I`.
Rendering uses GLAD/OpenGL and shaders in `data/shaders/`. UI is XML/Yoga based
with many `Node*` subclasses. Project files are PPI, brush packages are PPBR,
and Photoshop brushes import through ABR support.

Exceptions are disabled in app code. Public modernization APIs should return
explicit status/result objects.
