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/.claude-plugin/plugin.json

@@ -1,7 +1,7 @@
 {
   "name": "scribe",
   "description": "Scribe for Claude Code: connects the scribe MCP server, adds the hooks that deliver live project state and relevant records at the right moment, ships the shared client-neutral Scribe skills (using-scribe, writing-plans, reporting-back, systematic-debugging, verification, brainstorming, reusing-code, shape-accounting), and syncs your saved Scribe Processes as skills (/scribe:sync).",
-  "version": "2026.09.16.1211",
+  "version": "2026.09.16.1232",
   "author": {
     "name": "Bryan Van Deusen"
   },

plugin/hooks/scribe_after_write.sh

@@ -105,12 +105,9 @@ done <<< "$current"
 [ -n "$changed" ] || exit 0
 
 scribe_config || :   # sets url/token; the call below is guarded on them
-repo=$(git -C "$repo_root" remote get-url origin 2>/dev/null || true)
+scope=$(scribe_scope_query "$repo_root")
 repo_q=""
-if [ -n "$repo" ]; then
+[ -n "$scope" ] && repo_q="&${scope}"
-  enc=$(printf '%s' "$repo" | jq -sRr '@uri' 2>/dev/null) || enc=""
-  [ -n "$enc" ] && repo_q="&repo=${enc}"
-fi
 
 # The dedup channels are the PRE-write hook's files, on purpose (see header).
 state_dir="${TMPDIR:-/tmp}/scribe-priorart"

plugin/hooks/scribe_autoinject.sh

@@ -65,14 +65,11 @@ q=$(printf '%s' "$prompt" | head -c 2000)
 # worth retrieving against were exactly the ones silently dropped. -s slurps.
 q_enc=$(printf '%s' "$q" | jq -sRr '@uri' 2>/dev/null) || exit 0
 
-# Resolve the working repo's remote so the server can scope to the bound project.
+# Scope to this directory's project — a `.scribe` marker, else the git remote.
 repo_dir=${event_cwd:-${CLAUDE_PROJECT_DIR:-$PWD}}
-repo=$(git -C "$repo_dir" remote get-url origin 2>/dev/null || true)
+scope=$(scribe_scope_query "$repo_dir")
 repo_q=""
-if [ -n "$repo" ]; then
+[ -n "$scope" ] && repo_q="&${scope}"
-  enc=$(printf '%s' "$repo" | jq -sRr '@uri' 2>/dev/null) || enc=""
-  [ -n "$enc" ] && repo_q="&repo=${enc}"
-fi
 
 # Per-session dedup: ids already injected this session are skipped.
 state_dir="${TMPDIR:-/tmp}/scribe-autoinject"

plugin/hooks/scribe_defs.sh

@@ -19,6 +19,11 @@
 #   scribe_rules_live FILE     live rule ids from the exclusion ledger,
 #                              comma-joined; entries age out (#3751)
 #   scribe_rules_append FILE   stdin ids -> the ledger, timestamped
+#   scribe_scope_query DIR     `project_id=N` or `repo=<enc>` for DIR — the
+#                              project-scope key EVERY hook sends (#4085).
+#                              Helpers: scribe_marker_file, scribe_url_host,
+#                              scribe_marker_read (id<TAB>why-not),
+#                              scribe_marker_project (the id alone)
 #
 # Sourced, not executed: `. "$(dirname "${BASH_SOURCE[0]}")/scribe_defs.sh"`.
 
@@ -283,3 +288,124 @@ scribe_rules_append() {
   now=$(date +%s 2>/dev/null) || now=0
   awk -v ts="$now" 'NF { print $1 "\t" ts }' >> "$f" 2>/dev/null || true
 }
+
+# ---------------------------------------------------------------------------
+# WHICH PROJECT IS THIS DIRECTORY'S? (#4085)
+#
+# Every hook here scopes its request to a project, and until this existed all
+# six did it the same single way: `git remote get-url origin`, resolved
+# server-side through the repo bindings. That works well inside a bound repo
+# and not at all outside one — a session in a plain directory got no project
+# scope from ANY hook, silently, because the one key the whole chain turns on
+# only exists in a git repo.
+#
+# The second key is a `.scribe` file in the directory (or above it, the way
+# git finds its root), naming the project the work belongs to. It is a
+# POINTER, not a copy: an id and enough to check the id means what it says.
+# Nothing Scribe should be holding goes in it.
+#
+#   {"instance": "https://scribe.example.com", "project_id": 2,
+#    "project": "FabledScribe"}
+#
+#   instance    WHICH Scribe the id belongs to, and the reason this file is
+#               not just a number. A project id means nothing on its own: id 2
+#               is a different project on every instance, so a marker that
+#               travels — a copied directory, a shared machine, a repo someone
+#               else clones — would silently scope a session to the wrong
+#               project. Compared HOST-ONLY against the configured endpoint, so
+#               http/https and a trailing slash don't cause a false mismatch.
+#               A mismatch drops the id: no project beats the wrong project.
+#   project_id  the pointer itself. Required.
+#   project     a human label. NOTHING READS IT. It is there so the file
+#               answers "what is this?" when opened, and so a stale one is
+#               visible rather than inert.
+#
+# A bare integer is also accepted (`echo 2 > .scribe`), because it is what a
+# person writes by hand and it parses as JSON already. It skips the instance
+# check by having nothing to check — deliberate, and the reason the written
+# form carries `instance`.
+#
+# THE MARKER WINS over a git remote. Someone put the file there on purpose;
+# a remote is just where the code happens to be pushed. That also makes the
+# marker the way to override a binding for one directory.
+
+# Nearest `.scribe` at or above DIR. Walks up to the filesystem root, capped so
+# a pathological path cannot spin.
+scribe_marker_file() {
+  local dir="$1" depth=0
+  [ -n "$dir" ] || return 0
+  while [ "$depth" -lt 40 ]; do
+    [ -f "$dir/.scribe" ] && { printf '%s' "$dir/.scribe"; return 0; }
+    case "$dir" in ""|"/") return 0 ;; esac
+    dir=$(dirname -- "$dir" 2>/dev/null) || return 0
+    depth=$((depth + 1))
+  done
+  return 0
+}
+
+# Host of a URL, lowercased, port kept. "" for empty input.
+scribe_url_host() {
+  printf '%s' "${1:-}" \
+    | sed -e 's#^[A-Za-z][A-Za-z0-9+.-]*://##' -e 's#^[^/@]*@##' -e 's#[/?].*$##' \
+    | tr 'A-Z' 'a-z'
+}
+
+# Read a marker file: prints "ID<TAB>REASON", at most one of them non-empty.
+#
+#   "7\t"            use project 7
+#   "\tnames no …"   a file is there and deliberately NOT used; say why
+#   "\t"             no marker file at all — the ordinary case, say nothing
+#
+# One line rather than an id plus a global, because every caller reads this
+# through `$( )` and a global set inside a command substitution dies with the
+# subshell. The caller would then read an unset variable, which under the
+# `set -u` these hooks all run with aborts the hook and costs the whole
+# session's context — a failure far larger than the message it was fetching.
+scribe_marker_read() {
+  local f="$1" id inst want
+  [ -n "$f" ] && [ -f "$f" ] || { printf '\t'; return 0; }
+  command -v jq >/dev/null 2>&1 || { printf '\t'; return 0; }
+  # A bare integer is valid JSON, so one filter reads both forms.
+  id=$(jq -r 'if type=="number" then (.|floor|tostring)
+              elif type=="object" then (.project_id // empty | tostring)
+              else empty end' "$f" 2>/dev/null) || id=""
+  case "$id" in ''|*[!0-9]*) id="" ;; esac
+  if [ -z "$id" ] || [ "$id" = "0" ]; then
+    printf '\tnames no project_id'
+    return 0
+  fi
+  inst=$(jq -r 'if type=="object" then (.instance // empty) else empty end' "$f" 2>/dev/null) || inst=""
+  if [ -n "$inst" ]; then
+    want=$(scribe_url_host "${url:-}")
+    inst=$(scribe_url_host "$inst")
+    if [ -n "$want" ] && [ "$inst" != "$want" ]; then
+      printf '\tpoints at %s, but this session is configured for %s' "$inst" "$want"
+      return 0
+    fi
+  fi
+  printf '%s\t' "$id"
+}
+
+# Just the id a marker names, or "" — the half scribe_scope_query needs.
+scribe_marker_project() {
+  scribe_marker_read "$1" | cut -f1
+}
+
+# The query args identifying DIR's project — `project_id=N` or `repo=<enc>` —
+# with NO leading `?` or `&`, so each caller keeps its own separator. Empty
+# when neither key is available. Requires `url` to be set (scribe_config) for
+# the marker's instance check; without it a marker is still honoured, since an
+# unconfigured hook is not going to send the request anyway.
+scribe_scope_query() {
+  local dir="$1" id repo enc
+  id=$(scribe_marker_project "$(scribe_marker_file "$dir")")
+  if [ -n "$id" ]; then
+    printf 'project_id=%s' "$id"
+    return 0
+  fi
+  repo=$(git -C "$dir" remote get-url origin 2>/dev/null || true)
+  [ -n "$repo" ] || return 0
+  command -v jq >/dev/null 2>&1 || return 0
+  enc=$(printf '%s' "$repo" | jq -sRr '@uri' 2>/dev/null) || enc=""
+  [ -n "$enc" ] && printf 'repo=%s' "$enc"
+}

plugin/hooks/scribe_prior_art.sh

@@ -150,13 +150,10 @@ q=$(printf '%s' "$code" | head -c 1200)
 path_enc=$(printf '%s' "$rel_path" | jq -sRr '@uri' 2>/dev/null) || exit 0
 code_enc=$(printf '%s' "$q" | jq -sRr '@uri' 2>/dev/null) || code_enc=""
 
-# Resolve the working repo's remote so the server can scope to the bound project.
+# Scope to this directory's project — a `.scribe` marker, else the git remote.
-repo=$(git -C "$lookup_dir" remote get-url origin 2>/dev/null || true)
+scope=$(scribe_scope_query "$lookup_dir")
 repo_q=""
-if [ -n "$repo" ]; then
+[ -n "$scope" ] && repo_q="&${scope}"
-  enc=$(printf '%s' "$repo" | jq -sRr '@uri' 2>/dev/null) || enc=""
-  [ -n "$enc" ] && repo_q="&repo=${enc}"
-fi
 
 # Per-session dedup, in its own file rather than sharing auto-inject's. Each
 # surface shows a given snippet at most once per session, but they don't silence

plugin/hooks/scribe_report_check.sh

@@ -149,11 +149,8 @@ report() {
     enc=$(printf '%s' "$m" | jq -sRr '@uri' 2>/dev/null) || enc=""
     q="${q}&missing=${enc}"
   fi
-  repo=$(git -C "${event_cwd:-${CLAUDE_PROJECT_DIR:-$PWD}}" remote get-url origin 2>/dev/null || true)
+  scope=$(scribe_scope_query "${event_cwd:-${CLAUDE_PROJECT_DIR:-$PWD}}")
-  if [ -n "$repo" ]; then
+  [ -n "$scope" ] && q="${q}&${scope}"
-    enc=$(printf '%s' "$repo" | jq -sRr '@uri' 2>/dev/null) || enc=""
-    [ -n "$enc" ] && q="${q}&repo=${enc}"
-  fi
   curl -fsS --max-time 4 \
     -H "Authorization: Bearer ${token}" \
     "${url%/}/api/plugin/report-check?${q}" 2>/dev/null

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 "$repo" ]; then
+  [ -n "$scope" ] && q="?${scope}"
-    enc=$(printf '%s' "$repo" | jq -sRr '@uri' 2>/dev/null) || enc=""
-    [ -n "$enc" ] && q="?repo=${enc}"
-  fi
   body=$(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."

plugin/hooks/scribe_tool_rules.sh

@@ -63,11 +63,8 @@ tool_enc=$(printf '%s' "$tool_name" | jq -sRr '@uri' 2>/dev/null) || exit 0
 
 repo_q=""
 lookup_dir=${event_cwd:-${CLAUDE_PROJECT_DIR:-$PWD}}
-repo_remote=$(git -C "$lookup_dir" remote get-url origin 2>/dev/null || true)
+scope=$(scribe_scope_query "$lookup_dir")
-if [ -n "$repo_remote" ]; then
+[ -n "$scope" ] && repo_q="&${scope}"
-  repo_enc=$(printf '%s' "$repo_remote" | jq -sRr '@uri' 2>/dev/null) || repo_enc=""
-  [ -n "$repo_enc" ] && repo_q="&repo=${repo_enc}"
-fi
 
 # THE SHARED SESSION LEDGER, and the thing most worth getting right here.
 #

plugin/skills/using-scribe/SKILL.md

@@ -13,10 +13,23 @@ asked for.
 
 ## Do this first (every session)
 
-If the working repo maps to a Scribe project (you're in a known repo, or
+If the working directory maps to a Scribe project, call `enter_project(id)` —
-`list_repo_bindings` shows a binding), call `enter_project(id)` — it returns the
+it returns the project's goal, the milestones and open tasks worked on most
-project's goal, the milestones and open tasks worked on most recently, its
+recently, its Systems and the titles of its own rules in one shot.
-Systems and the titles of its own rules in one shot.
+
+**A directory does not have to be a git repo to have a project.** A repo is
+bound by its remote (`list_repo_bindings` shows the bindings). Anything else —
+a notes folder, a server's config directory, a scratch directory — is bound by
+a `.scribe` file naming the project:
+
+    {"instance": "https://scribe.example.com", "project_id": 2, "project": "Homelab"}
+
+`instance` is what makes the id trustworthy. An id means nothing on its own —
+it is a different project on every Scribe — so a marker that has travelled to
+another instance is ignored rather than followed to the wrong project. A bare
+`2` also works when writing the file by hand. When work plainly belongs to a
+project and the directory names none, offer to write the marker;
+`list_projects` has the id.
 
 Then **ask before you act**: before anything hard to reverse or outward-facing,
 search the rules for what you are about to do. Reflex 2 below is why asking,

src/scribe/routes/plugin.py

@@ -64,8 +64,11 @@ async def session_context():
             resolves it to the bound project (see services/repo_bindings); an
             unbound repo yields a "bind this repo" hint instead. This is how the
             active project is determined — the plugin never pins a project id.
-        project_id (optional int) — explicit override, mainly for manual/ad-hoc
+        project_id (optional int) — the project named directly, and the only
-            curl testing; takes precedence over `repo` when set.
+            key a caller outside a git repo has (#4085): the plugin's hooks
+            send it when a `.scribe` marker file names a project. Takes
+            precedence over `repo`. Access-checked like any other read — an id
+            this account cannot read loads no project rather than failing.
     """
     project_id, _repo, unbound_repo = await _project_scope()
     result = await plugin_ctx_svc.build_session_context(

src/scribe/services/plugin_context.py

@@ -2171,7 +2171,10 @@ async def build_session_context(
     Args:
         user_id: the operator.
         project_id: the resolved active project (0 = none). The endpoint
-            resolves this from the working repo's remote, not from config.
+            resolves this from the working repo's remote, or from a `.scribe`
+            marker file naming the project directly — the only key a session
+            outside a git repo has (#4085). A non-zero id that does not
+            resolve is reported rather than silently dropped.
         unbound_repo: when the hook sent a repo remote that maps to no project,
             its normalized key — triggers a one-line "bind this repo" hint so
             the binding is self-healing.
@@ -2241,18 +2244,34 @@ async def build_session_context(
                         f"`get_design_system({design['id']})` → "
                         f"`resolved_guidance`.",
                     ]
-    elif unbound_repo:
+    # Nothing loaded — say which nothing (#4085). This used to hang off the
-        lines += [
+    # `if project_id:` above as an `elif`, which meant an id that was SENT and
-            "",
+    # did not resolve produced no message at all: the outer branch was taken,
-            "## Repository not yet bound",
+    # the inner one was not, and the caller got a context that simply omitted
-            f"This repo (`{unbound_repo}`) isn't mapped to a Scribe project, so "
+    # the project it had asked for. That is the one case worth being loudest
-            "no project context was loaded. Bind it once with "
+    # about, because the caller is holding a pointer it believes in.
-            f'`bind_repo(repo_url="{unbound_repo}", project_id=<id>)` '
+    if project_dict is None:
-            "(call `list_projects` to find the id) and future sessions here will "
+        if project_id:
-            "auto-load that project's context.",
+            lines += [
-        ]
+                "",
-    else:
+                f"## Project {project_id} could not be loaded",
-        lines += ["", "No Scribe project is bound to this working directory."]
+                f"This session asked for project {project_id}, but this account "
+                "cannot read it — the id may belong to a different Scribe "
+                "instance, or the project may have been deleted. "
+                "`list_projects` shows what is readable here.",
+            ]
+        elif unbound_repo:
+            lines += [
+                "",
+                "## Repository not yet bound",
+                f"This repo (`{unbound_repo}`) isn't mapped to a Scribe project, so "
+                "no project context was loaded. Bind it once with "
+                f'`bind_repo(repo_url="{unbound_repo}", project_id=<id>)` '
+                "(call `list_projects` to find the id) and future sessions here will "
+                "auto-load that project's context.",
+            ]
+        else:
+            lines += ["", "No Scribe project is bound to this working directory."]
 
     context = "\n".join(line for line in lines if line is not None)
     if len(context) > _MAX_CHARS:

tests/test_scribe_marker.py

@@ -0,0 +1,150 @@
+"""`.scribe` — the second key a directory can be scoped by (#4085).
+
+Every hook in `plugin/hooks/` scopes its request to a project, and until this
+existed all six turned on one key: `git remote get-url origin`. That key does
+not exist outside a git repo, so a session in a plain directory was unscoped
+everywhere at once — silently, because a missing remote is indistinguishable
+from a remote nobody bound.
+
+`scribe_scope_query` is the shared answer, so these run the real shell rather
+than a reimplementation of it. What they pin:
+
+  * the marker is found from a subdirectory, the way git finds its root;
+  * a bare integer works, because that is what a person writes by hand;
+  * the marker BEATS a git remote, since someone put the file there on purpose;
+  * an `instance` naming a different Scribe is refused — the case the field
+    exists for. A project id means nothing on its own: id 2 is a different
+    project on every instance, so a marker that travels would otherwise scope
+    the session to the wrong project, confidently and without a word.
+
+That last one is the reason the file is JSON and not a number, so it is tested
+from both directions: the matching host is honoured, the mismatched one is not.
+"""
+from __future__ import annotations
+
+import json
+import os
+import shutil
+import subprocess
+from pathlib import Path
+
+import pytest
+
+ROOT = Path(__file__).resolve().parents[1]
+DEFS = ROOT / "plugin" / "hooks" / "scribe_defs.sh"
+INSTANCE = "https://scribe.example.com"
+
+
+def _sh(script: str, cwd: Path, env_extra: dict | None = None) -> str:
+    for tool in ("bash", "jq"):
+        if shutil.which(tool) is None:
+            pytest.skip(f"hook runtime tool {tool!r} not installed")
+    env = {"PATH": os.environ["PATH"], "HOME": str(cwd)}
+    env.update(env_extra or {})
+    body = f'set -uo pipefail\n. "{DEFS}"\nurl="{INSTANCE}"\n{script}\n'
+    out = subprocess.run(["bash", "-c", body], cwd=cwd, capture_output=True,
+                         text=True, env=env, timeout=30)
+    assert out.returncode == 0, out.stderr
+    return out.stdout.strip()
+
+
+def _marker(d: Path, **fields) -> None:
+    (d / ".scribe").write_text(json.dumps(fields))
+
+
+def _git_repo(d: Path, remote: str) -> None:
+    env = {"PATH": os.environ["PATH"], "HOME": str(d)}
+    subprocess.run(["git", "init", "-q"], cwd=d, check=True, env=env)
+    subprocess.run(["git", "remote", "add", "origin", remote], cwd=d, check=True, env=env)
+
+
+def test_a_bare_integer_is_a_valid_marker(tmp_path):
+    """What someone writes by hand. It parses as JSON already, so one filter
+    reads it and the written form alike."""
+    (tmp_path / ".scribe").write_text("7\n")
+    assert _sh(f'scribe_scope_query "{tmp_path}"', tmp_path) == "project_id=7"
+
+
+def test_the_marker_is_found_from_a_subdirectory(tmp_path):
+    _marker(tmp_path, instance=INSTANCE, project_id=2, project="FabledScribe")
+    deep = tmp_path / "src" / "scribe" / "services"
+    deep.mkdir(parents=True)
+    assert _sh(f'scribe_scope_query "{deep}"', tmp_path) == "project_id=2"
+
+
+def test_a_matching_instance_is_honoured(tmp_path):
+    """Host-only comparison, so http/https and a trailing slash are not a
+    mismatch — only a genuinely different Scribe is."""
+    _marker(tmp_path, instance="http://scribe.example.com/", project_id=2)
+    assert _sh(f'scribe_scope_query "{tmp_path}"', tmp_path) == "project_id=2"
+
+
+def test_a_marker_for_another_instance_is_refused_with_a_reason(tmp_path):
+    """The case the `instance` field exists for. No project beats the wrong
+    project, and the reason is carried so the session can say which it was."""
+    _marker(tmp_path, instance="https://someone-elses.example.org", project_id=2)
+    assert _sh(f'scribe_scope_query "{tmp_path}"', tmp_path) == ""
+    said = _sh(f'scribe_marker_read "{tmp_path}/.scribe"', tmp_path)
+    assert "someone-elses.example.org" in said and "scribe.example.com" in said
+
+
+def test_the_marker_beats_a_git_remote(tmp_path):
+    """Someone put the file there deliberately; a remote is only where the
+    code happens to be pushed. This is also how a directory overrides its
+    binding."""
+    _git_repo(tmp_path, "git@git.example.com:someone/thing.git")
+    assert _sh(f'scribe_scope_query "{tmp_path}"', tmp_path).startswith("repo=")
+    _marker(tmp_path, instance=INSTANCE, project_id=2)
+    assert _sh(f'scribe_scope_query "{tmp_path}"', tmp_path) == "project_id=2"
+
+
+def test_without_a_marker_the_git_remote_still_answers(tmp_path):
+    """The path every existing install is on — it must not have moved."""
+    _git_repo(tmp_path, "git@git.example.com:someone/thing.git")
+    got = _sh(f'scribe_scope_query "{tmp_path}"', tmp_path)
+    assert got.startswith("repo=") and "git.example.com" in got.replace("%2F", "/")
+
+
+def test_a_plain_directory_with_no_marker_scopes_to_nothing(tmp_path):
+    """Not an error — the caller sends no scope and the server says so."""
+    assert _sh(f'scribe_scope_query "{tmp_path}"', tmp_path) == ""
+
+
+@pytest.mark.parametrize("body", ["", "not json at all", "{}", '{"project_id": 0}',
+                                  '{"project_id": "../../etc"}', "[1,2,3]"])
+def test_an_unusable_marker_is_refused_rather_than_sent(tmp_path, body):
+    """A marker is operator-written and can say anything. Nothing that is not
+    a positive integer may reach the query string."""
+    (tmp_path / ".scribe").write_text(body)
+    assert _sh(f'scribe_scope_query "{tmp_path}"', tmp_path) == ""
+
+
+def test_the_reason_survives_the_command_substitution_that_fetches_it(tmp_path):
+    """Regression on a bug this nearly shipped with.
+
+    The reason used to be a global the function set, which every caller reads
+    through `$( )` — a subshell, so the assignment died with it and the caller
+    saw an UNSET variable. The hooks all run `set -u`, where reading one aborts
+    the script: a directory with a misaddressed marker would have cost the
+    session its entire SessionStart context, to fetch a warning about a file.
+
+    So the reason comes back through stdout with the id, and this asserts on
+    the shape the caller actually uses: read in a subshell, split, and used
+    under `set -u` without the shell dying.
+    """
+    _marker(tmp_path, instance="https://elsewhere.example.org", project_id=2)
+    got = _sh(
+        f'read_out=$(scribe_marker_read "$(scribe_marker_file "{tmp_path}")")\n'
+        'printf "id=[%s] why=[%s]" "${read_out%%$\'\\t\'*}" "${read_out#*$\'\\t\'}"',
+        tmp_path,
+    )
+    assert got.startswith("id=[]")
+    assert "elsewhere.example.org" in got
+
+
+def test_the_walk_up_terminates_at_the_root(tmp_path):
+    """No marker anywhere above: the loop must end rather than spin. tmp_path
+    is several levels down from /, so this really does walk."""
+    deep = tmp_path / "a" / "b" / "c"
+    deep.mkdir(parents=True)
+    assert _sh(f'scribe_scope_query "{deep}"', tmp_path) == ""

tests/test_services_plugin_context.py

@@ -215,6 +215,31 @@ async def test_build_session_context_unbound_repo_emits_bind_hint():
     assert "## Active project" not in ctx
 
 
+@pytest.mark.asyncio
+async def test_a_project_id_that_does_not_resolve_is_reported_not_dropped():
+    """A `.scribe` marker names a project directly (#4085), so for the first
+    time a caller arrives holding a pointer it BELIEVES in. If the id is for
+    another instance, or names a deleted project, the session has to be told —
+    it cannot infer it from an absence.
+
+    This used to render nothing whatsoever: the branch hung off `if project_id`
+    as an `elif`, so an id that was sent and failed took the outer arm, found
+    no project, and fell out of the block having said nothing at all.
+    """
+    from scribe.services.plugin_context import build_session_context
+    with patch("scribe.services.plugin_context.projects_svc.get_project",
+               AsyncMock(return_value=None)):
+        out = await build_session_context(user_id=7, project_id=41)
+
+    ctx = out["context"]
+    assert out["project"] is None
+    assert "## Project 41 could not be loaded" in ctx
+    assert "list_projects" in ctx
+    # Not mistaken for the repo case, which has a different remedy.
+    assert "## Repository not yet bound" not in ctx
+    assert "No Scribe project is bound" not in ctx
+
+
 @pytest.mark.asyncio
 async def test_build_process_manifest_renders_stub_specs():
     items = [