session-memory: distributor base + Artifact (WP-0007 T01)

distribute/base.py: Artifact dataclass + Distributor protocol + idempotent
BEGIN/END snippet markers (upsert_block replaces a pattern's block in place so
re-distribution doesn't duplicate) + agnostic markdown body rendering from
SolutionPattern fields. BaseDistributor honours per-flavor body/target hints.
8 new tests; suite 110/110.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/test_distribute_base.py

@@ -0,0 +1,88 @@
+"""Distributor base tests (WP-0007 T01): markers, idempotent upsert, rendering."""
+
+import os
+import sys
+
+sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
+
+from session_memory.curate.schema import Resolution, SolutionPattern  # noqa: E402
+from session_memory.distribute.base import (  # noqa: E402
+    Artifact,
+    BaseDistributor,
+    Distributor,
+    render_markdown_body,
+    upsert_block,
+    wrap_block,
+)
+
+
+def _pattern(pid="sp-x", polarity="problem"):
+    return SolutionPattern(
+        id=pid, name="Read before edit", version="1.2.0", polarity=polarity,
+        problem="Agents edit files they have not read.",
+        resolutions=[Resolution(summary="Read the file first", detail="then Edit",
+                                steps=["Read", "Edit"])],
+        rendering_hints={"claude": {"target": "CLAUDE.md"}},
+    )
+
+
+def test_render_markdown_body_has_problem_and_resolution():
+    body = render_markdown_body(_pattern())
+    assert "### Read before edit" in body
+    assert "Agents edit files" in body
+    assert "**Avoid:**" in body  # problem polarity
+    assert "- Read the file first — then Edit" in body
+    assert "  - Read" in body
+
+
+def test_success_polarity_label():
+    assert "**Prefer:**" in render_markdown_body(_pattern(polarity="success"))
+
+
+def test_wrap_block_has_markers_and_version():
+    block = wrap_block("sp-x", "hello", "1.2.0")
+    assert block.startswith("<!-- BEGIN helix-forge pattern:sp-x --> v1.2.0")
+    assert block.rstrip().endswith("<!-- END helix-forge pattern:sp-x -->")
+
+
+def test_upsert_inserts_then_replaces_in_place():
+    doc = "# Title\n\nsome text\n"
+    b1 = wrap_block("sp-x", "first", "1")
+    once = upsert_block(doc, "sp-x", b1)
+    assert "first" in once and once.count("BEGIN helix-forge pattern:sp-x") == 1
+    # re-distributing the same id replaces, does not duplicate
+    b2 = wrap_block("sp-x", "second", "2")
+    twice = upsert_block(once, "sp-x", b2)
+    assert "second" in twice and "first" not in twice
+    assert twice.count("BEGIN helix-forge pattern:sp-x") == 1
+
+
+def test_upsert_keeps_other_patterns():
+    doc = upsert_block("", "sp-a", wrap_block("sp-a", "A"))
+    doc = upsert_block(doc, "sp-b", wrap_block("sp-b", "B"))
+    assert "sp-a" in doc and "sp-b" in doc
+
+
+def test_base_distributor_renders_artifact():
+    d = BaseDistributor(flavor="claude", target_path="CLAUDE.md")
+    art = d.render(_pattern())
+    assert isinstance(art, Artifact)
+    assert isinstance(d, Distributor)  # satisfies the protocol
+    assert art.flavor == "claude"
+    assert art.target_path == "CLAUDE.md"
+    assert "BEGIN helix-forge pattern:sp-x" in art.content
+    assert "Read before edit" in art.content
+
+
+def test_body_hint_overrides_default():
+    p = _pattern()
+    p.rendering_hints["claude"]["body"] = "custom claude body"
+    d = BaseDistributor(flavor="claude", target_path="CLAUDE.md")
+    assert "custom claude body" in d.render(p).content
+
+
+def test_target_hint_overrides_default():
+    p = _pattern()
+    p.rendering_hints["claude"]["target"] = "docs/CLAUDE.md"
+    d = BaseDistributor(flavor="claude", target_path="CLAUDE.md")
+    assert d.render(p).target_path == "docs/CLAUDE.md"