build: wikitool new project - Seite und Tracker-Projekt unter einem Namen (#126)

Files changed:
- CHANGES.md
- VERSION
- tools/CONTRACT.md
- tools/chemenu/commands/new_page.py
- tools/chemenu/errors.py
- tools/chemenu/review.py
- tools/chemenu/tasks/__init__.py
- tools/chemenu/tests/test_new_page.py

tools/chemenu/tasks/__init__.py

@@ -4,9 +4,43 @@
 loops (#119 D1). This package is the one place `wikitool` crosses that line -
 never an instruction, never a second MCP server (#119 D25): a provider is a
 Python object behind `chemenu.tasks.protocol.TaskReader`/`TaskWriter`, and
-everything above this package (the future `wikitool review`/`new project`
-commands, #125/#126) talks to that protocol and nothing provider-specific.
+everything above this package (`wikitool review`/`new project`, #125/#126)
+talks to that protocol and nothing provider-specific.
 
 No command lives here yet - this package is a library, per #124's own scope
 note ("Kein Kommando. Diese Schicht ist Bibliothek").
+
+`build_reader`/`build_writer` below are the one dispatch table from
+`TasksConfig.provider` to a concrete adapter, shared by `chemenu.review`
+(#125) and `chemenu.commands.new_page`'s `project` handling (#126) - kept in
+one place per `AGENTS.md` invariant 8, rather than two copies of the same
+`if cfg.provider == "superproductivity": ...` drifting apart.
 """
+from __future__ import annotations
+
+from chemenu.errors import ValidationError
+from chemenu.tasks.config import TasksConfig
+from chemenu.tasks.protocol import TaskReader, TaskWriter
+
+
+def build_reader(cfg: TasksConfig) -> TaskReader:
+    """Dispatch on `cfg.provider` to a concrete `TaskReader`."""
+    if cfg.provider == "superproductivity":
+        from chemenu.tasks import superproductivity as sp
+
+        sp_cfg = sp.SuperProductivityConfig.from_dict(cfg.provider_config)
+        return sp.SuperProductivityReader(sp_cfg)
+    raise ValidationError(f"No reader is wired up for task provider {cfg.provider!r}.")
+
+
+def build_writer(cfg: TasksConfig, reader: TaskReader) -> TaskWriter:
+    """Dispatch on `cfg.provider` to a concrete `TaskWriter`, over an
+    already-built `reader` - a writer that needs to re-check the read path
+    (e.g. `SuperProductivityWriter`'s own collision preflight) reads through
+    the same object its caller does, rather than opening a second one."""
+    if cfg.provider == "superproductivity":
+        from chemenu.tasks import superproductivity as sp
+
+        sp_cfg = sp.SuperProductivityConfig.from_dict(cfg.provider_config)
+        return sp.SuperProductivityWriter(sp_cfg, reader)
+    raise ValidationError(f"No writer is wired up for task provider {cfg.provider!r}.")