docs(6205): forge comments state the reason, not the instance that taught it

The module header drops the milestone/step map and record citations; the
per-user optionality, the keyring model and the empty-selector baseline are
stated as present-tense facts.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/scribe/services/forge.py

@@ -1,25 +1,24 @@
 """Forge adapter — optional server-side READ access to the operator's git forge.
 
-Step 4 of milestone 288 (#2689, decision #2686). The recorded location of a
-snippet is the source of truth for its code and the stored body is a cache;
-this module is the seam that lets the SERVER read that source of truth, so the
-cache can be refreshed at pull time (step 5), drift can be flagged from push
-webhooks (step 6), and coverage can be measured (step 7).
+The recorded location of a snippet is the source of truth for its code and
+the stored body is a cache; this module is the seam that lets the SERVER read
+that source of truth, so the cache can be refreshed at pull time, drift can be
+flagged from push webhooks, and coverage can be measured.
 
 Design constraints, in force everywhere below:
 
-  - OPTIONAL per user (rule #115, sharpened by #2778). Connections are
+  - OPTIONAL per user. Connections are
     per-user keyring rows resolved by repo host on the PROJECT OWNER's
     keyring; `get_forges()` returns an empty selector when the owner has
-    nothing configured, and every consumer must treat that as "keep today's
-    behavior". A user who never configures a forge is not degraded — that is
+    nothing configured, and every consumer must treat that as "behave as if
+    there were no forge". A user who never configures a forge is not degraded — that is
     the baseline.
   - READ-ONLY by construction. The adapter exposes reads; there is no write
     method to misuse. The token an operator mints for it only ever needs read
     scope, and the docs say so.
-  - The contract stays as small as its consumers (steps 5-7): read_file /
+  - The contract stays as small as its consumers: read_file /
     latest_commit / archive / default_branch / resolve_repo / check. Two
-    implementations (Gitea, GitHub — step 8) keep it honest; resist widening
+    implementations (Gitea, GitHub) keep it honest; resist widening
     it speculatively.
   - Repo identity is the repo-binding key — `normalize_repo_key`'s
     host/owner/repo — so the join between a snippet's recorded repo and the
@@ -53,12 +52,12 @@ logger = logging.getLogger(__name__)
 FORGE_KINDS = ("gitea", "github")
 
 # Total budget per forge call. Consumers either have a cache to fall back to
-# (step 5) or a user watching a button (the test probe) — neither tolerates a
+# or a user watching a button (the test probe) — neither tolerates a
 # hung socket, and there is no retry: the fallback IS the retry policy.
 _TIMEOUT = httpx.Timeout(5.0)
 
 # Archive downloads move a whole-repo tarball and only ever run off the
-# request path (coverage recompute, step 7), so they get a bigger budget than
+# request path (coverage recompute), so they get a bigger budget than
 # the per-file reads — but still a bound, because a hung background task
 # holds a connection slot as surely as a foreground one.
 _ARCHIVE_TIMEOUT = httpx.Timeout(60.0)
@@ -79,13 +78,13 @@ class ForgeFile:
     """One file read from the forge at a specific point in history."""
 
     content: str
-    # The commit the content was served at — what provenance stores (#2688).
+    # The commit the content was served at — what provenance stores.
     commit_sha: str
     path: str
 
 
 def host_of(url: str) -> str:
-    """The lowercase hostname of a URL — the keyring's lookup key (#2778)."""
+    """The lowercase hostname of a URL — the keyring's lookup key."""
     return (urlsplit(url).hostname or "").lower()
 
 
@@ -199,7 +198,7 @@ class ForgeAdapter:
     async def latest_commit(self, repo: str, path: str, ref: str = "") -> str:
         """The newest commit touching ``path`` — "" when it can't be told.
 
-        The cached-SHA short-circuit (#2693): when a snippet's provenance
+        The cached-SHA short-circuit: when a snippet's provenance
         already names a commit, this one small call can prove the file
         hasn't moved since — no content transfer, which is what keeps
         pull-time freshness inside GitHub's rate limits.
@@ -213,7 +212,7 @@ class ForgeAdapter:
     async def archive(self, repo: str, ref: str) -> bytes:
         """The repo's content at ``ref`` as a gzipped tarball, in one request.
 
-        Coverage measurement (step 7) needs every source file's text; per-file
+        Coverage measurement needs every source file's text; per-file
         reads would mean one API call per file, so the archive endpoint is the
         only shape that scales past toy repos. Callers must never run this in
         a request path — it moves the whole repo.
@@ -287,8 +286,8 @@ class GiteaForge(ForgeAdapter):
 
 
 class GitHubForge(ForgeAdapter):
-    """The GitHub implementation — the second one, which is the point (#2693):
-    it proves the seam is a contract rather than a Gitea-shaped hole. Works
+    """The GitHub implementation — the second one, which is the point: it
+    proves the seam is a contract rather than a Gitea-shaped hole. Works
     against github.com and GitHub Enterprise; the token is a fine-grained PAT
     with Contents: Read-only (or a classic token with `repo` read)."""
 
@@ -379,8 +378,8 @@ def build_adapter(
 ) -> ForgeAdapter | None:
     """One validated adapter from raw connection values, or None.
 
-    None means "this connection cannot serve reads" — the same contract the
-    old instance-wide lookup had, applied per keyring row. Misconfigurations
+    None means "this connection cannot serve reads", decided per keyring
+    row. Misconfigurations
     are logged, never raised: a bad row must not break the reads the good
     rows can still serve.
     """
@@ -403,13 +402,13 @@ def build_adapter(
 
 @dataclass(frozen=True)
 class ForgeSelector:
-    """The forge reads available to one project owner (#2778).
+    """The forge reads available to one project owner.
 
     Consumers ask it to serve a REPO, not to hand over "the forge": resolve()
     walks the owner's adapters and returns the (adapter, api_repo) pair for
     the first one whose host serves the repo — or None, which every consumer
-    treats exactly as the old "no forge configured" state. An empty selector
-    IS rule #115's baseline.
+    treats exactly as "no forge configured". An empty selector is the
+    baseline every install starts from, not a degraded mode.
     """
 
     adapters: tuple[ForgeAdapter, ...] = ()
@@ -431,7 +430,7 @@ async def get_forges(
 ) -> ForgeSelector:
     """The forge selector for reads on behalf of ``owner_id``'s records.
 
-    The keyring model (#2778): every server-side forge read for a record runs
+    The keyring model: every server-side forge read for a record runs
     on the PROJECT OWNER's connections, resolved by repo host — a forge token
     is a user's credential, and one user's reads must never ride another
     user's token. Pass the record's ``project_id`` so the per-project pin