Overhaul docs retrieval and web search quality

Replace the abandoned llms-txt-mcp/Chroma docs backend with an in-repo
MCP service: SQLite WAL + FTS5 + sentence-transformer embeddings,
transactional source replacement, persisted state across restarts,
singleflight refresh with conditional requests, hybrid lexical/semantic
ranking with exact-duplicate collapse, source/host filters, and
explicit-by-default content retrieval. Add docs_rebuild and a
docs-rebuild CLI command.

Add deterministic llms-full.txt snapshot generation for machine-local
menus with hash-validated provenance manifests; lifecycle commands
promote a local menu to its snapshot only when the manifest validates.
Switch public source profiles to content-bearing llms-full.txt feeds.

Improve web search: bounded provider fallback with per-attempt
diagnostics and cancellation, an optional Brave Search API provider,
strict SearXNG engine selection, capped link/media extraction, and a
real engine=browser renderer that routes every request through the
existing SSRF vetting while blocking WebSockets, non-GET traffic, and
private destinations.

Extend release checks with offline unit suites and isolated candidate
container tests for both images.

docker/docs/tests/test_service.py

@@ -0,0 +1,98 @@
+from __future__ import annotations
+
+import tempfile
+import unittest
+from pathlib import Path
+
+import numpy as np
+
+from context_docs.models import PreparedDocument, RefreshOutcome, SourceUpdate
+from context_docs.search import HybridSearch
+from context_docs.service import DocsService
+from context_docs.store import IndexStore
+
+from .fakes import FakeEmbedder
+
+
+class NoopRefresh:
+    async def refresh(self, source: str, force: bool = False) -> RefreshOutcome:
+        return RefreshOutcome(source, "fresh", 1)
+
+
+class ServiceTest(unittest.IsolatedAsyncioTestCase):
+    async def asyncSetUp(self) -> None:
+        self.tmp = tempfile.TemporaryDirectory()
+        self.store = IndexStore(Path(self.tmp.name) / "docs.sqlite3")
+        self.source = "https://example.test/llms.txt"
+        self.store.configure_sources([self.source])
+        content = "IMMICH_IGNORE_MOUNT_CHECK_ERRORS " + "x" * 200
+        item = PreparedDocument(
+            id="exact",
+            configured_source=self.source,
+            resolved_source=self.source,
+            source_host="example.test",
+            canonical_url="https://docs.example.test/environment",
+            canonical_host="docs.example.test",
+            title="Environment",
+            description="",
+            heading_path="Environment",
+            content=content,
+            content_hash="content-hash",
+            embedding=np.asarray([1.0, 0.0, 0.0, 0.0], dtype=np.float32),
+        )
+        self.store.replace_source(
+            SourceUpdate(
+                configured_source=self.source,
+                resolved_source=self.source,
+                etag=None,
+                last_modified=None,
+                body_hash="body",
+                raw_body="# body",
+                parser_fingerprint="context-docs-parser-v1",
+                embedding_fingerprint="fake-embedder-v1",
+                checked_at=1.0,
+                indexed_at=1.0,
+                stale_at=9_999_999_999.0,
+                documents=[item],
+            )
+        )
+        embedder = FakeEmbedder()
+        self.service = DocsService(
+            self.store,
+            HybridSearch(self.store, embedder),
+            NoopRefresh(),
+            max_get_bytes=100,
+        )
+
+    async def asyncTearDown(self) -> None:
+        self.store.close()
+        self.tmp.cleanup()
+
+    async def test_query_does_not_retrieve_content_by_default(self) -> None:
+        response = await self.service.query("IMMICH_IGNORE_MOUNT_CHECK_ERRORS")
+
+        self.assertEqual({}, response["retrieved_content"])
+        self.assertEqual("exact", response["search_results"][0]["id"])
+
+    async def test_explicit_retrieval_respects_global_byte_cap(self) -> None:
+        response = await self.service.query(
+            "IMMICH_IGNORE_MOUNT_CHECK_ERRORS",
+            retrieve_ids=["exact"],
+            max_bytes=10_000,
+        )
+        retrieved = response["retrieved_content"]["exact"]
+
+        self.assertLessEqual(len(retrieved["content"].encode()), 100)
+        self.assertTrue(retrieved["truncated"])
+
+    async def test_high_default_threshold_only_retrieves_strong_hybrid_match(self) -> None:
+        response = await self.service.query(
+            "IMMICH_IGNORE_MOUNT_CHECK_ERRORS",
+            auto_retrieve=True,
+        )
+
+        self.assertIn("exact", response["retrieved_content"])
+
+
+if __name__ == "__main__":
+    unittest.main()