feat(m1): add pinned workspace root and ASCII slug helpers

Plan Step 3. Verify green: `.venv/bin/python -m pytest tests/test_paths.py` ->
8 passed, exit 0. Full suite: 11 passed.

Test first, and RED was observed before a line of paths.py existed
(ModuleNotFoundError on collection).

Two measured risks drive the design, not one.

Risk C6 -- the host-side server runs unsandboxed with caller-supplied paths.
safe_join resolves BOTH operands with os.path.realpath before comparing, so
lexical traversal and symlink escape fall to the same check; a lexical check on
the joined string would have called the symlink case safe. The comparison is
component-aware, so a sibling whose name merely prefixes the root is outside.
Escape raises; it never clamps to an adjacent path.

Risk H8 -- macOS hands back NFD. slug normalises to NFC first, so a decomposed
name and its composed twin produce one slug rather than two directories. The
test asserts that equality on a real NFC/NFD pair, not on a lookalike.

No implicit default workspace: --workspace, else JOBBSOK_WORKSPACE, else a
`workspace:` line in ${CLAUDE_PLUGIN_DATA}/jobbsok.conf, else WorkspaceUnresolved.
Guessing at the operator's home directory is the one behaviour this module must
not have. This tightens build-brief section 5's `~/jobbsok-workspace` default
into an explicit order; the deviation is recorded in the plan's Assumptions.

scaffold is idempotent by only creating what is absent -- an existing
beslutninger.jsonl is never truncated. It is append-only, and a scaffold that
emptied it would destroy the decision log. The test proves this by populating
the workspace and asserting a byte-identical snapshot across a second run.

Collision rule is documented and tested: -2, then -3, counting up.

sak_id carries no `taken` parameter. An earlier draft had one; no step and no
test requires it, so it was unproven code and was removed rather than kept.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

scripts/jobbsok_lib/__init__.py

@@ -0,0 +1,6 @@
+"""Shared library for the jobbsok scripts.
+
+Deliberately thin. Everything here is imported by scripts that run both from
+the Claude Code CLI and from the host-side MCP server, so nothing heavy is
+imported at module load: cold start is a real constraint on the server side.
+"""

scripts/jobbsok_lib/paths.py

@@ -0,0 +1,268 @@
+"""Workspace root resolution, path containment, and name generation.
+
+Every later script depends on this module, and it exists because of two
+measured risks.
+
+Risk C6 -- the host-side MCP server runs unsandboxed on the operator's machine
+and takes caller-supplied paths. A path that escapes the workspace escapes onto
+the machine. There are two ways out, lexical traversal and symlink resolution,
+and a check that only looks at the joined string catches the first and misses
+the second. `safe_join` resolves with `os.path.realpath` before comparing, so
+both are refused, and refused loudly: the failure is an exception, never a
+clamped path that silently writes somewhere adjacent.
+
+Risk H8 -- macOS returns filenames in NFD, so a name that looks identical to
+its NFC twin is a different byte string, and two cases that should be one
+become two directories. `slug` normalises first and then folds to ASCII, so no
+generated path component carries a non-ASCII byte at all.
+
+There is no implicit default workspace. `workspace_root` resolves from
+`--workspace`, else `JOBBSOK_WORKSPACE`, else a `workspace:` line in
+`${CLAUDE_PLUGIN_DATA}/jobbsok.conf`; if none of the three answers, that is an
+error. Guessing at the operator's home directory is the one behaviour this
+module must never have. (This tightens build-brief section 5's
+`~/jobbsok-workspace` default into an explicit resolution order; the deviation
+is recorded in the plan's Assumptions.)
+"""
+
+import os
+import re
+import unicodedata
+
+#: Directories created by :func:`scaffold`, relative to the workspace root.
+WORKSPACE_DIRS = (
+    "profil",
+    "profil/cv",
+    "saker",
+    "arkiv",
+    "karantene",
+    "kandidater",
+    ".review",
+)
+
+#: Files created by :func:`scaffold`, relative to the workspace root.
+WORKSPACE_FILES = (
+    "beslutninger.jsonl",
+    "referanser.md",
+    ".gitignore",
+)
+
+#: `sak-id` format from build-brief section 5.2: YYYY-MM-<slug>.
+SAK_ID_RE = re.compile(r"^\d{4}-\d{2}-[a-z0-9-]{1,80}$")
+
+CONF_FILENAME = "jobbsok.conf"
+CONF_KEY = "workspace:"
+
+# Folds applied before Unicode decomposition, because these characters have no
+# canonical decomposition to strip a mark from: the ash and the o-slash are
+# distinct letters, not accented vowels. The a-ring does decompose and is
+# handled by the general pass, but is listed here so the three folds the
+# contract names are visible in one place.
+_FOLDS = {
+    "æ": "ae",  # ae ligature
+    "Æ": "ae",
+    "ø": "o",   # o with stroke
+    "Ø": "o",
+    "å": "a",   # a with ring
+    "Å": "a",
+    "ß": "ss",  # sharp s, for German employer names
+    "đ": "d",   # d with stroke
+    "Đ": "d",
+}
+
+
+class WorkspaceError(Exception):
+    """Base class for every refusal in this module."""
+
+
+class WorkspaceUnresolved(WorkspaceError):
+    """No workspace could be resolved, and guessing one is not an option."""
+
+
+class WorkspaceEscape(WorkspaceError):
+    """A path resolved outside the pinned workspace root."""
+
+
+class InvalidSakId(WorkspaceError):
+    """A sak-id did not match the build-brief section 5.2 format."""
+
+
+def workspace_root(arg=None, environ=None):
+    """Resolve the workspace root once, and pin it.
+
+    Resolution order, first hit wins:
+
+    1. ``arg`` -- the caller's ``--workspace`` value.
+    2. ``JOBBSOK_WORKSPACE`` in the environment.
+    3. A single ``workspace: <path>`` line in
+       ``${CLAUDE_PLUGIN_DATA}/jobbsok.conf``, written by the scaffold. This
+       exists so the operator does not retype an absolute path in every Cowork
+       invocation.
+
+    Raises :class:`WorkspaceUnresolved` if none of the three answers. The
+    returned path is absolute and symlink-resolved, and it need not exist yet --
+    scaffolding a fresh workspace is a supported first run.
+    """
+    environ = os.environ if environ is None else environ
+
+    candidate = _clean(arg)
+    if candidate is None:
+        candidate = _clean(environ.get("JOBBSOK_WORKSPACE"))
+    if candidate is None:
+        candidate = _from_conf(environ)
+    if candidate is None:
+        raise WorkspaceUnresolved(
+            "no workspace: pass --workspace, set JOBBSOK_WORKSPACE, or put a "
+            "'workspace: <path>' line in ${CLAUDE_PLUGIN_DATA}/%s. There is no "
+            "default -- guessing at your home directory is not a fallback."
+            % CONF_FILENAME
+        )
+    return os.path.realpath(os.path.expanduser(candidate))
+
+
+def safe_join(root, *parts):
+    """Join ``parts`` under ``root`` and refuse anything that leaves it.
+
+    Both operands are resolved with :func:`os.path.realpath` before comparing,
+    so lexical traversal (``../..``) and symlink escape are refused by the same
+    check. The comparison is component-aware: a sibling directory whose name
+    merely starts with the root's name is outside, not inside.
+    """
+    resolved_root = os.path.realpath(os.path.expanduser(root))
+    candidate = os.path.realpath(os.path.join(resolved_root, *parts))
+    if candidate != resolved_root and not candidate.startswith(resolved_root + os.sep):
+        raise WorkspaceEscape(
+            "path escapes the workspace: %r resolves to %r, which is outside %r"
+            % (os.path.join(*parts) if parts else "", candidate, resolved_root)
+        )
+    return candidate
+
+
+def slug(text, taken=None):
+    """Fold ``text`` into a lowercase ASCII path component.
+
+    Normalises to NFC first so a decomposed macOS name and its composed twin
+    produce the same slug (risk H8), applies the Norwegian folds -- ``ae`` for
+    the ash, ``o`` for the o-slash, ``a`` for the a-ring -- then strips any
+    remaining combining marks and replaces every run of non-alphanumeric
+    characters with a single hyphen.
+
+    Collision rule: when ``taken`` is supplied and the slug is already in it,
+    a numeric suffix is appended, starting at ``-2`` and counting up
+    (``bergen-kommune``, ``bergen-kommune-2``, ``bergen-kommune-3``). The
+    suffix is part of the name, so it is stable once assigned; callers keep
+    ``taken`` and add each returned slug to it.
+    """
+    text = unicodedata.normalize("NFC", text or "")
+    folded = "".join(_FOLDS.get(char, char) for char in text)
+    # Anything left with an accent loses it here (e -acute becomes e); anything
+    # that survives as non-ASCII is dropped by the ASCII round-trip below.
+    decomposed = unicodedata.normalize("NFD", folded)
+    stripped = "".join(c for c in decomposed if not unicodedata.combining(c))
+    ascii_only = stripped.encode("ascii", "ignore").decode("ascii")
+    base = re.sub(r"[^a-z0-9]+", "-", ascii_only.lower()).strip("-")
+    if not base:
+        raise ValueError("slug of %r is empty; a path component cannot be blank" % (text,))
+
+    if taken is None or base not in taken:
+        return base
+    suffix = 2
+    while "%s-%d" % (base, suffix) in taken:
+        suffix += 1
+    return "%s-%d" % (base, suffix)
+
+
+def sak_id(year_month, arbeidsgiver, rolle):
+    """Build a `sak-id`: ``YYYY-MM-<arbeidsgiver-slug>-<rolle-slug>``.
+
+    ``year_month`` is validated rather than trusted, because a malformed month
+    here becomes a directory name that no later glob will find.
+    """
+    if not re.match(r"^\d{4}-\d{2}$", year_month or ""):
+        raise InvalidSakId("year_month must be YYYY-MM, got %r" % (year_month,))
+    return validate_sak_id(
+        "%s-%s-%s" % (year_month, slug(arbeidsgiver), slug(rolle))
+    )
+
+
+def sak_dirname(year_month, arbeidsgiver, rolle):
+    """The workspace-relative directory for a case: ``saker/<sak-id>``."""
+    return "saker/%s" % sak_id(year_month, arbeidsgiver, rolle)
+
+
+def validate_sak_id(value):
+    """Return ``value`` if it matches :data:`SAK_ID_RE`, else raise."""
+    if not SAK_ID_RE.match(value or ""):
+        raise InvalidSakId(
+            "sak-id %r does not match %s" % (value, SAK_ID_RE.pattern)
+        )
+    return value
+
+
+def scaffold(root):
+    """Create the build-brief section 5 workspace tree under ``root``.
+
+    Idempotent: re-running over a populated workspace changes nothing. Files
+    are created only when absent, so an existing ``beslutninger.jsonl`` is
+    never truncated -- it is append-only, and a scaffold that emptied it would
+    destroy the decision log.
+
+    Returns the list of workspace-relative paths this call actually created.
+    """
+    root = os.path.realpath(os.path.expanduser(root))
+    created = []
+
+    for relative in (".",) + WORKSPACE_DIRS:
+        target = os.path.join(root, relative) if relative != "." else root
+        if not os.path.isdir(target):
+            os.makedirs(target)
+            if relative != ".":
+                created.append(relative)
+
+    for relative in WORKSPACE_FILES:
+        target = os.path.join(root, relative)
+        if os.path.exists(target):
+            continue
+        with open(target, "w", encoding="utf-8") as handle:
+            handle.write(_initial_content(relative))
+        created.append(relative)
+
+    return created
+
+
+def _initial_content(relative):
+    if relative == "beslutninger.jsonl":
+        # Append-only log. Empty, not absent: the difference matters at the
+        # first append, and an absent file reads as "never scaffolded".
+        return ""
+    if relative == "referanser.md":
+        return "# Referanser\n"
+    if relative == ".gitignore":
+        return (
+            "# This workspace is never committed. It holds the operator's own\n"
+            "# job search: listings, applications, correspondence, decisions.\n"
+            "*\n"
+        )
+    raise ValueError("no initial content defined for %r" % (relative,))
+
+
+def _clean(value):
+    if value is None:
+        return None
+    value = value.strip()
+    return value or None
+
+
+def _from_conf(environ):
+    data_dir = _clean(environ.get("CLAUDE_PLUGIN_DATA"))
+    if data_dir is None:
+        return None
+    conf = os.path.join(os.path.expanduser(data_dir), CONF_FILENAME)
+    if not os.path.isfile(conf):
+        return None
+    with open(conf, "r", encoding="utf-8") as handle:
+        for line in handle:
+            line = line.strip()
+            if line.startswith(CONF_KEY):
+                return _clean(line[len(CONF_KEY):])
+    return None