feat(plugin): a directory says which project it belongs to, git repo or not (#4085)

All six hooks scoped their requests one way: `git remote get-url origin`,
resolved server-side through the repo bindings. That key does not exist
outside a git repo, so a session in a plain directory was unscoped in every
hook at once — no project context, no prior-art scoping, no project rules —
and silently, because a missing remote is indistinguishable from a remote
nobody bound.

A `.scribe` file is the second key, read by the shared scribe_scope_query so a
directory scopes the same way everywhere:

    {"instance": "https://scribe.example.com", "project_id": 2, "project": "…"}

`instance` is why the file is not just a number: an id is a different project
on every Scribe, so a marker that travels — a copied directory, a shared
machine, a repo someone else clones — would otherwise scope the session to the
wrong project without a word. Compared host-only, and a mismatch drops the id:
no project beats the wrong project. A bare integer is accepted too, since it
is what a person writes by hand. The marker beats a git remote — someone put
the file there on purpose — which is also how a directory overrides its
binding.

Two things it found on the way:

  * An explicit project_id that did not resolve rendered NO message at all —
    the branch hung off `if project_id` as an `elif`, so a caller holding a
    pointer it believed in got a context that silently omitted the project it
    had asked for. Now reported.
  * The refusal reason was a global set inside a function every caller reads
    through `$( )`. The assignment died with the subshell, leaving the caller
    to read an unset variable under `set -u` — which aborts the hook and costs
    the whole session's SessionStart context, to fetch a warning about a file.
    It comes back through stdout with the id instead, and a test pins it.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01821k5B3Ysecp9fNYs92Kuy

plugin/hooks/scribe_session_context.sh

@@ -151,14 +151,19 @@ scribe_config || :
 dyn=""
 status=""
 if [ -n "$url" ] && [ -n "$token" ] && command -v curl >/dev/null 2>&1; then
-  # Resolve the working repo's remote so the server can map it to a project.
+  # Which project is this directory's? A `.scribe` marker first, then the git
+  # remote (#4085). scribe_scope_query answers that, and is shared with the
+  # other five hooks so a directory scopes the same way everywhere; the pieces
+  # are re-read here only to explain what happened when nothing resolved.
   repo_dir=${CLAUDE_PROJECT_DIR:-$PWD}
+  marker=$(scribe_marker_file "$repo_dir")
+  marker_read=$(scribe_marker_read "$marker")
+  marker_id=${marker_read%%$'\t'*}
+  marker_why=${marker_read#*$'\t'}
   repo=$(git -C "$repo_dir" remote get-url origin 2>/dev/null || true)
+  scope=$(scribe_scope_query "$repo_dir")
   q=""
-  if [ -n "$repo" ]; then
-    enc=$(printf '%s' "$repo" | jq -sRr '@uri' 2>/dev/null) || enc=""
-    [ -n "$enc" ] && q="?repo=${enc}"
-  fi
+  [ -n "$scope" ] && q="?${scope}"
   body=$(curl -fsS --max-time 8 \
     -H "Authorization: Bearer ${token}" \
     "${url%/}/api/plugin/context${q}" 2>/dev/null) || body=""
@@ -184,6 +189,29 @@ fi
 [ -n "$dyn" ]    && append "$dyn"
 [ -n "$status" ] && append "$status"
 
+# --- Nothing resolved: say WHICH nothing, and what would fix it (#4085) ---
+#
+# The server can say "no project is bound to this working directory", and
+# until now that was the whole answer. It is the same sentence for a directory
+# that is not a repo, a repo whose remote nobody bound, and a marker file
+# naming a project this account cannot read — three different problems with
+# three different fixes, and no way to tell them apart from inside the session.
+#
+# The marker is the adapter's convention, so the adapter explains it: the
+# server reports whether a project resolved, and this hook — which knows what
+# it sent and why — turns that into the sentence the operator can act on. The
+# repo case is left to the server's existing "bind this repo" hint.
+if [ -n "$dyn" ] && [ -z "$(printf '%s' "$body" | jq -r '.project.id // empty' 2>/dev/null)" ]; then
+  host=$(scribe_url_host "$url")
+  if [ -n "$marker_why" ]; then
+    append "> ⚠️ Scribe: the marker file \`${marker}\` ${marker_why}, so no project context was loaded. Fix the file, or ignore it and bind this directory another way."
+  elif [ -n "$marker_id" ]; then
+    append "> ⚠️ Scribe: \`${marker}\` names project ${marker_id}, which this account cannot read on ${host} — it may belong to a different Scribe instance, or the project may have been deleted. Check with \`list_projects()\` and correct the file."
+  elif [ -z "$repo" ]; then
+    append "> ℹ️ Scribe: this directory is not a git repository and has no \`.scribe\` marker, so no project context was loaded — every hook this session is unscoped. If this work belongs to a Scribe project, call \`list_projects()\` and write the marker: \`{\"instance\": \"${url%/}\", \"project_id\": <id>, \"project\": \"<title>\"}\` in \`${repo_dir}/.scribe\`. Future sessions here load that project on their own."
+  fi
+fi
+
 # Compaction re-grounding: lead with a reload banner when this fire is a compact.
 if [ "$source" = "compact" ]; then
   prepend "> ⟳ This session was just COMPACTED — earlier turns are now a summary, so in-flight detail may be lost. Any rules that had been retrieved went into that summary with everything else, so treat yourself as holding none: before the next consequential act, ask again with \`search(content_type=\"rule\")\` rather than trusting a half-remembered one. Re-run \`enter_project()\` for the active project, check its recent milestones and open tasks, and reconcile what you are mid-way through against what Scribe records. Scribe is the record."