feat(arch01): atomic platform install + authority kernel (Closes #822)

ARCH-01 Foundation Slice A — first implementation leaf of the #820/#821
program. Adds a new, disabled-by-default SQLite kernel:

- Connection-bound trusted-service actor context (cp_actor_principal/kind,
  cp_operation_mode, cp_service_session, cp_context_epoch) that SQL may read
  but never set; every mutating trigger runs the actor protocol and fails
  closed on a missing, stale, or epoch-shifted context.
- Immutable authority-dominance lattice with the exact seeded tuple set,
  validated individually by the install-state trigger.
- Principal-equivalence root: a class exists before its first principal and
  current_class_id is NOT NULL.
- Single atomic BEGIN IMMEDIATE install seeding the installer principal, the
  distinguished operator-key issuer, dominance, the initial NULL-grantor
  bootstrap grant, the active invariant, and the immutable installed marker
  last; second install returns ALREADY_INSTALLED with no mutation.
- Immutability triggers on marker/seed/dominance/issuer/installer
  registration/initial-grant identity; append-only audit_records; last-active
  grant floored by CHECK so concurrent revokes cannot drop it to zero.

Files: arch01_platform.py (new), tests/test_arch01_platform.py (new).

Tests: 25 tests + 21 subtests cover ACs 1-14 including negative, rollback,
raw-write-bypass, and concurrency. Focused suite green; full suite 4422
passed / 11 pre-existing baseline failures at 53c2c92, zero new.

Subsystem disabled by default until readiness checks pass. SQLite-first;
PostgreSQL parity is #827.

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>

arch01_platform.py

@@ -0,0 +1,892 @@
+"""ARCH-01 Foundation Slice A — atomic platform installation + authority kernel (#822).
+
+Parents: #820, #821. **First implementation leaf of the ARCH-01 program.**
+
+This module implements the smallest executable ARCH-01 foundation:
+
+* a connection-bound authenticated actor context (``cp_actor_*`` /
+  ``cp_operation_mode`` / ``cp_context_epoch`` SQLite scalar functions that SQL
+  may *read* but can never *set* — ``[TRUSTED-SERVICE]`` authenticity);
+* an immutable authority-dominance lattice with an exact seeded tuple set
+  (``[SCHEMA]``);
+* the principal-equivalence root (a class exists *before* its first principal;
+  ``principals.current_class_id`` is ``NOT NULL``; ``[SCHEMA]``);
+* a single-transaction platform installation that seeds the initial
+  ``platform.bootstrap`` grant and an immutable ``installed`` marker, validated
+  by a fail-closed ``install_state`` ``BEFORE INSERT`` trigger (``[SCHEMA]``).
+
+Everything else in the ARCH-01/02/04 program (evidence stores, repository
+bindings, workspaces, PostgreSQL parity, full grant succession, full principal
+merge) is out of scope here and tracked in its own issue — see #822 §5/§17.
+
+**Readiness / production posture.** This subsystem is *disabled by default*.
+Nothing in the running MCP server imports or enables it. It becomes a security
+boundary only once its readiness checks (the ACs in #822) pass in the target
+environment. Instantiating :class:`PlatformKernel` creates an isolated SQLite
+database and never touches the operational control-plane store.
+
+Enforcement classification (per #820 vocabulary):
+
+* ``[TRUSTED-SERVICE]`` — actor-context authenticity: the scalar functions are
+  registered by the trusted Python process; SQL cannot define or redefine them.
+* ``[SCHEMA]`` — fail-closed aborts, the dominance/immutability/NOT-NULL-class/
+  last-active-grant invariants, enforced by CHECK/FK/trigger.
+* ``[RUNTIME-ADAPTER]`` — *none* in this slice.
+
+SQLite-first. ``BEGIN IMMEDIATE`` serializes concurrent installs and concurrent
+grant/revoke on the singleton invariant row. PostgreSQL parity is a distinct
+issue (#827); this module does **not** claim it.
+"""
+
+from __future__ import annotations
+
+import os
+import sqlite3
+import threading
+from contextlib import contextmanager
+from dataclasses import dataclass
+from datetime import datetime, timezone
+from typing import Iterator, Optional
+
+# --------------------------------------------------------------------------- #
+# Closed enumerations (#822 §4).
+# --------------------------------------------------------------------------- #
+
+ACTOR_KINDS = ("operator", "supervisor", "service", "installer")
+OPERATION_MODES = ("normal", "install", "merge", "internal_service")
+
+# Exact seeded authority-dominance tuple set (#822 §4). This set is normative:
+# the install-state trigger rejects any missing, additional, or malformed tuple.
+DOMINANCE_TUPLES = (
+    ("platform.bootstrap", "platform.bootstrap"),
+    ("platform.bootstrap", "project.admin"),
+    ("platform.bootstrap", "supervisor.root.establish"),
+    ("supervisor.root", "supervisor.register"),
+    ("supervisor.root", "supervisor.verify"),
+    ("supervisor.root", "supervisor.recover"),
+)
+
+# The distinguished operator-key issuer seeded during install.
+DISTINGUISHED_ISSUER_KIND = "operator-key"
+DISTINGUISHED_ISSUER_ID = "platform.bootstrap.operator-key"
+
+# Structured result codes (#822 §10).
+INSTALLED = "INSTALLED"
+ALREADY_INSTALLED = "ALREADY_INSTALLED"
+INVALID_ACTOR_CONTEXT = "INVALID_ACTOR_CONTEXT"
+INVALID_BOOTSTRAP_STATE = "INVALID_BOOTSTRAP_STATE"
+DOMINANCE_SET_MISMATCH = "DOMINANCE_SET_MISMATCH"
+AUTHORIZATION_DENIED = "AUTHORIZATION_DENIED"
+CONCURRENT_INSTALLATION_LOST = "CONCURRENT_INSTALLATION_LOST"
+
+# Required audit events (#822 §14).
+EVT_PLATFORM_INSTALLED = "platform_installed"
+EVT_GRANT_CREATED = "platform_grant_created"
+EVT_GRANT_REVOKED = "platform_grant_revoked"
+EVT_PRINCIPAL_REGISTERED = "principal_registered"
+
+SCHEMA_VERSION = 1
+
+DB_PATH_ENV = "ARCH01_PLATFORM_DB"
+
+
+class PlatformKernelError(RuntimeError):
+    """Base class for structured, code-bearing kernel failures."""
+
+    def __init__(self, code: str, message: str = "") -> None:
+        super().__init__(message or code)
+        self.code = code
+
+
+class ActorContextError(PlatformKernelError):
+    """Raised when a mutation is attempted without a valid actor context."""
+
+
+# --------------------------------------------------------------------------- #
+# Schema (#822 §6). Tables + fail-closed triggers.
+#
+# Every *mutating* trigger opens with the actor protocol: read the context
+# epoch, read the actor fields, and abort unless the context is present,
+# non-null, mode/kind well-formed, and epoch-consistent with the active
+# transaction. The scalar functions ``cp_*`` are registered from Python only;
+# SQL has no statement that can set them, which is the trusted-service boundary.
+# --------------------------------------------------------------------------- #
+
+_ACTOR_KINDS_SQL = ", ".join("'%s'" % k for k in ACTOR_KINDS)
+_OP_MODES_SQL = ", ".join("'%s'" % m for m in OPERATION_MODES)
+
+# Actor-protocol predicate: TRUE when the context is INVALID and the trigger
+# must abort. ``cp_actor_context_valid()`` folds "present + non-expired +
+# live-epoch == bound-epoch" (the read/re-read epoch equality of #822 §4) into
+# one trusted-service answer; the remaining reads assert field well-formedness.
+_INVALID_ACTOR = (
+    "cp_actor_context_valid() IS NOT 1 "
+    "OR cp_context_epoch() IS NULL "
+    "OR cp_actor_principal() IS NULL "
+    "OR cp_actor_kind() NOT IN (%s) "
+    "OR cp_operation_mode() NOT IN (%s)" % (_ACTOR_KINDS_SQL, _OP_MODES_SQL)
+)
+
+_ACTOR_GUARD = (
+    "SELECT CASE WHEN (%s) "
+    "THEN RAISE(ABORT, 'INVALID_ACTOR_CONTEXT') END;" % _INVALID_ACTOR
+)
+
+# require_installed: abort a privileged mutation when there is no install
+# marker and we are not currently installing (#822 §4).
+_REQUIRE_INSTALLED = (
+    "SELECT CASE WHEN ((SELECT COUNT(*) FROM install_state) = 0 "
+    "AND cp_operation_mode() <> 'install') "
+    "THEN RAISE(ABORT, 'NOT_INSTALLED') END;"
+)
+
+_SCHEMA_SQL = f"""
+PRAGMA foreign_keys = ON;
+
+CREATE TABLE IF NOT EXISTS arch01_meta (
+    key TEXT PRIMARY KEY,
+    value TEXT NOT NULL
+);
+
+-- Equivalence classes are created BEFORE their first principal (#822 §4).
+CREATE TABLE IF NOT EXISTS principal_equivalence_classes (
+    class_id INTEGER PRIMARY KEY AUTOINCREMENT,
+    created_at TEXT NOT NULL
+);
+
+CREATE TABLE IF NOT EXISTS authoritative_issuers (
+    issuer_id INTEGER PRIMARY KEY AUTOINCREMENT,
+    issuer_kind TEXT NOT NULL,
+    issuer_ref TEXT NOT NULL,
+    created_at TEXT NOT NULL,
+    UNIQUE (issuer_kind, issuer_ref)
+);
+
+-- current_class_id is NOT NULL: a principal cannot exist without a class
+-- (#822 AC6). issuer_id is nullable ONLY for the installer during install
+-- (#822 AC7), enforced by trg_principals_null_issuer below.
+CREATE TABLE IF NOT EXISTS principals (
+    principal_id TEXT PRIMARY KEY,
+    actor_kind TEXT NOT NULL CHECK (actor_kind IN ({_ACTOR_KINDS_SQL})),
+    current_class_id INTEGER NOT NULL REFERENCES principal_equivalence_classes(class_id),
+    issuer_id INTEGER REFERENCES authoritative_issuers(issuer_id),
+    registered_by TEXT REFERENCES principals(principal_id),
+    created_at TEXT NOT NULL
+);
+
+CREATE TABLE IF NOT EXISTS authority_dominance (
+    dominant TEXT NOT NULL,
+    subordinate TEXT NOT NULL,
+    PRIMARY KEY (dominant, subordinate)
+);
+
+CREATE TABLE IF NOT EXISTS platform_bootstrap_seed (
+    seed_id INTEGER PRIMARY KEY CHECK (seed_id = 1),
+    installer_principal_id TEXT NOT NULL REFERENCES principals(principal_id),
+    created_at TEXT NOT NULL
+);
+
+CREATE TABLE IF NOT EXISTS platform_bootstrap_grants (
+    grant_id INTEGER PRIMARY KEY AUTOINCREMENT,
+    grantee_principal_id TEXT NOT NULL REFERENCES principals(principal_id),
+    granted_by TEXT REFERENCES principals(principal_id),
+    active INTEGER NOT NULL DEFAULT 1 CHECK (active IN (0, 1)),
+    created_at TEXT NOT NULL,
+    revoked_at TEXT
+);
+
+-- Singleton row; active_count floored at 1 by CHECK so the last active grant
+-- can never be revoked (#822 AC11).
+CREATE TABLE IF NOT EXISTS platform_active_invariant (
+    id INTEGER PRIMARY KEY CHECK (id = 1),
+    active_count INTEGER NOT NULL CHECK (active_count >= 1)
+);
+
+-- The immutable install marker; inserted LAST in the install transaction.
+CREATE TABLE IF NOT EXISTS install_state (
+    id INTEGER PRIMARY KEY CHECK (id = 1),
+    marker TEXT NOT NULL CHECK (marker = 'installed'),
+    installed_at TEXT NOT NULL
+);
+
+-- Append-only (#822 AC14).
+CREATE TABLE IF NOT EXISTS audit_records (
+    audit_id INTEGER PRIMARY KEY AUTOINCREMENT,
+    event TEXT NOT NULL,
+    principal_id TEXT,
+    detail TEXT,
+    created_at TEXT NOT NULL
+);
+
+-- ------------------------------------------------------------------------- --
+-- Actor protocol on every mutating trigger (#822 §4, [SCHEMA] fail-closed).
+-- ------------------------------------------------------------------------- --
+
+CREATE TRIGGER IF NOT EXISTS trg_classes_actor
+BEFORE INSERT ON principal_equivalence_classes
+BEGIN
+    {_ACTOR_GUARD}
+END;
+
+CREATE TRIGGER IF NOT EXISTS trg_issuers_actor
+BEFORE INSERT ON authoritative_issuers
+BEGIN
+    {_ACTOR_GUARD}
+END;
+
+CREATE TRIGGER IF NOT EXISTS trg_principals_actor
+BEFORE INSERT ON principals
+BEGIN
+    {_ACTOR_GUARD}
+END;
+
+CREATE TRIGGER IF NOT EXISTS trg_dominance_actor
+BEFORE INSERT ON authority_dominance
+BEGIN
+    {_ACTOR_GUARD}
+END;
+
+CREATE TRIGGER IF NOT EXISTS trg_seed_actor
+BEFORE INSERT ON platform_bootstrap_seed
+BEGIN
+    {_ACTOR_GUARD}
+END;
+
+CREATE TRIGGER IF NOT EXISTS trg_grants_actor_insert
+BEFORE INSERT ON platform_bootstrap_grants
+BEGIN
+    {_ACTOR_GUARD}
+    {_REQUIRE_INSTALLED}
+END;
+
+CREATE TRIGGER IF NOT EXISTS trg_grants_actor_update
+BEFORE UPDATE ON platform_bootstrap_grants
+BEGIN
+    {_ACTOR_GUARD}
+END;
+
+CREATE TRIGGER IF NOT EXISTS trg_invariant_actor_insert
+BEFORE INSERT ON platform_active_invariant
+BEGIN
+    {_ACTOR_GUARD}
+END;
+
+CREATE TRIGGER IF NOT EXISTS trg_invariant_actor_update
+BEFORE UPDATE ON platform_active_invariant
+BEGIN
+    {_ACTOR_GUARD}
+END;
+
+CREATE TRIGGER IF NOT EXISTS trg_audit_actor
+BEFORE INSERT ON audit_records
+BEGIN
+    {_ACTOR_GUARD}
+END;
+
+-- ------------------------------------------------------------------------- --
+-- NOT-NULL-issuer exception for the installer only (#822 AC7).
+-- A NULL issuer_id is accepted solely for an installer principal during
+-- install mode, before the marker exists; any other NULL-issuer principal is
+-- rejected. install-time issuer linkage (installer -> distinguished issuer)
+-- is applied by a later UPDATE, permitted while no marker exists.
+-- ------------------------------------------------------------------------- --
+
+CREATE TRIGGER IF NOT EXISTS trg_principals_null_issuer
+BEFORE INSERT ON principals
+WHEN NEW.issuer_id IS NULL
+BEGIN
+    SELECT CASE WHEN NOT (
+        NEW.actor_kind = 'installer'
+        AND cp_operation_mode() = 'install'
+        AND (SELECT COUNT(*) FROM install_state) = 0
+        AND (SELECT COUNT(*) FROM principals WHERE issuer_id IS NULL) = 0
+    ) THEN RAISE(ABORT, 'INVALID_BOOTSTRAP_STATE') END;
+END;
+
+-- ------------------------------------------------------------------------- --
+-- Post-install immutability of the authority root (#822 §4, AC9).
+-- Registration fields freeze only AFTER the marker exists, so the install
+-- transaction's own installer issuer-linkage UPDATE is permitted.
+-- ------------------------------------------------------------------------- --
+
+CREATE TRIGGER IF NOT EXISTS trg_principals_frozen_update
+BEFORE UPDATE ON principals
+WHEN (SELECT COUNT(*) FROM install_state) > 0
+BEGIN
+    SELECT RAISE(ABORT, 'IMMUTABLE_PRINCIPAL');
+END;
+
+CREATE TRIGGER IF NOT EXISTS trg_principals_frozen_delete
+BEFORE DELETE ON principals
+BEGIN
+    SELECT RAISE(ABORT, 'IMMUTABLE_PRINCIPAL');
+END;
+
+-- Distinguished issuer identity is immutable once written.
+CREATE TRIGGER IF NOT EXISTS trg_issuers_immutable_update
+BEFORE UPDATE ON authoritative_issuers
+BEGIN
+    SELECT RAISE(ABORT, 'IMMUTABLE_ISSUER');
+END;
+
+CREATE TRIGGER IF NOT EXISTS trg_issuers_immutable_delete
+BEFORE DELETE ON authoritative_issuers
+BEGIN
+    SELECT RAISE(ABORT, 'IMMUTABLE_ISSUER');
+END;
+
+-- The dominance lattice is immutable once seeded.
+CREATE TRIGGER IF NOT EXISTS trg_dominance_immutable_update
+BEFORE UPDATE ON authority_dominance
+BEGIN
+    SELECT RAISE(ABORT, 'IMMUTABLE_DOMINANCE');
+END;
+
+CREATE TRIGGER IF NOT EXISTS trg_dominance_immutable_delete
+BEFORE DELETE ON authority_dominance
+BEGIN
+    SELECT RAISE(ABORT, 'IMMUTABLE_DOMINANCE');
+END;
+
+-- The bootstrap seed is immutable once written.
+CREATE TRIGGER IF NOT EXISTS trg_seed_immutable_update
+BEFORE UPDATE ON platform_bootstrap_seed
+BEGIN
+    SELECT RAISE(ABORT, 'IMMUTABLE_SEED');
+END;
+
+CREATE TRIGGER IF NOT EXISTS trg_seed_immutable_delete
+BEFORE DELETE ON platform_bootstrap_seed
+BEGIN
+    SELECT RAISE(ABORT, 'IMMUTABLE_SEED');
+END;
+
+-- The install marker is immutable once written.
+CREATE TRIGGER IF NOT EXISTS trg_install_state_immutable_update
+BEFORE UPDATE ON install_state
+BEGIN
+    SELECT RAISE(ABORT, 'IMMUTABLE_INSTALL_STATE');
+END;
+
+CREATE TRIGGER IF NOT EXISTS trg_install_state_immutable_delete
+BEFORE DELETE ON install_state
+BEGIN
+    SELECT RAISE(ABORT, 'IMMUTABLE_INSTALL_STATE');
+END;
+
+-- Grants: identity is immutable; the ONLY permitted mutation is a single
+-- active 1 -> 0 revocation (#822 §4 initial-grant identity immutability +
+-- grant/revoke). Reactivation and identity edits are rejected.
+CREATE TRIGGER IF NOT EXISTS trg_grants_identity_frozen
+BEFORE UPDATE ON platform_bootstrap_grants
+WHEN NOT (
+    NEW.grant_id = OLD.grant_id
+    AND NEW.grantee_principal_id = OLD.grantee_principal_id
+    AND NEW.granted_by IS OLD.granted_by
+    AND NEW.created_at = OLD.created_at
+    AND OLD.active = 1
+    AND NEW.active = 0
+)
+BEGIN
+    SELECT RAISE(ABORT, 'IMMUTABLE_GRANT');
+END;
+
+CREATE TRIGGER IF NOT EXISTS trg_grants_no_delete
+BEFORE DELETE ON platform_bootstrap_grants
+BEGIN
+    SELECT RAISE(ABORT, 'IMMUTABLE_GRANT');
+END;
+
+-- audit_records is append-only.
+CREATE TRIGGER IF NOT EXISTS trg_audit_immutable_update
+BEFORE UPDATE ON audit_records
+BEGIN
+    SELECT RAISE(ABORT, 'IMMUTABLE_AUDIT');
+END;
+
+CREATE TRIGGER IF NOT EXISTS trg_audit_immutable_delete
+BEFORE DELETE ON audit_records
+BEGIN
+    SELECT RAISE(ABORT, 'IMMUTABLE_AUDIT');
+END;
+
+-- ------------------------------------------------------------------------- --
+-- install_state BEFORE INSERT: validate the whole bootstrap atomically
+-- (#822 §4, AC4). Each dominance tuple is checked individually; a missing,
+-- additional, or malformed tuple -> DOMINANCE_SET_MISMATCH. The seed<->installer
+-- link, the single active NULL-grantor installer grant, the installer's
+-- non-NULL issuer, the active invariant, and "no extra principal created under
+-- the NULL-issuer exception" -> INVALID_BOOTSTRAP_STATE.
+-- ------------------------------------------------------------------------- --
+
+CREATE TRIGGER IF NOT EXISTS trg_install_state_validate
+BEFORE INSERT ON install_state
+BEGIN
+    SELECT CASE WHEN NOT (
+        (SELECT COUNT(*) FROM authority_dominance) = {len(DOMINANCE_TUPLES)}
+        AND EXISTS (SELECT 1 FROM authority_dominance WHERE dominant='platform.bootstrap' AND subordinate='platform.bootstrap')
+        AND EXISTS (SELECT 1 FROM authority_dominance WHERE dominant='platform.bootstrap' AND subordinate='project.admin')
+        AND EXISTS (SELECT 1 FROM authority_dominance WHERE dominant='platform.bootstrap' AND subordinate='supervisor.root.establish')
+        AND EXISTS (SELECT 1 FROM authority_dominance WHERE dominant='supervisor.root' AND subordinate='supervisor.register')
+        AND EXISTS (SELECT 1 FROM authority_dominance WHERE dominant='supervisor.root' AND subordinate='supervisor.verify')
+        AND EXISTS (SELECT 1 FROM authority_dominance WHERE dominant='supervisor.root' AND subordinate='supervisor.recover')
+    ) THEN RAISE(ABORT, 'DOMINANCE_SET_MISMATCH') END;
+
+    SELECT CASE WHEN NOT (
+        (SELECT COUNT(*) FROM platform_bootstrap_seed) = 1
+        AND (SELECT COUNT(*) FROM principals) = 1
+        AND (SELECT actor_kind FROM principals
+             WHERE principal_id = (SELECT installer_principal_id FROM platform_bootstrap_seed WHERE seed_id = 1)
+            ) = 'installer'
+        AND (SELECT issuer_id FROM principals
+             WHERE principal_id = (SELECT installer_principal_id FROM platform_bootstrap_seed WHERE seed_id = 1)
+            ) IS NOT NULL
+        AND (SELECT COUNT(*) FROM platform_bootstrap_grants
+             WHERE granted_by IS NULL AND active = 1
+               AND grantee_principal_id = (SELECT installer_principal_id FROM platform_bootstrap_seed WHERE seed_id = 1)
+            ) = 1
+        AND (SELECT COUNT(*) FROM platform_bootstrap_grants) = 1
+        AND (SELECT active_count FROM platform_active_invariant WHERE id = 1) = 1
+    ) THEN RAISE(ABORT, 'INVALID_BOOTSTRAP_STATE') END;
+END;
+"""
+
+
+def default_db_path() -> str:
+    return os.environ.get(
+        DB_PATH_ENV,
+        os.path.expanduser("~/.cache/gitea-tools/arch01/platform.sqlite3"),
+    )
+
+
+def _utc_now_iso() -> str:
+    return datetime.now(timezone.utc).strftime("%Y-%m-%dT%H:%M:%SZ")
+
+
+@dataclass(frozen=True)
+class OperationResult:
+    """Structured result of a kernel operation (#822 §10)."""
+
+    code: str
+    detail: str = ""
+
+    @property
+    def ok(self) -> bool:
+        return self.code in (INSTALLED, ALREADY_INSTALLED)
+
+
+@dataclass
+class _ActorContext:
+    principal: str
+    kind: str
+    mode: str
+    session: Optional[str]
+    bound_epoch: int
+    live_epoch: int
+    expired: bool = False
+
+
+class PlatformKernel:
+    """ARCH-01 authority kernel over a single SQLite connection.
+
+    The connection carries the trusted-service actor context: the ``cp_*``
+    scalar functions read the context this object holds. Only Python code here
+    can bind or clear it, so no SQL statement can assert an actor identity — the
+    trusted-service authenticity boundary of #822 §4.
+    """
+
+    def __init__(self, db_path: Optional[str] = None, *, busy_timeout_ms: int = 5000) -> None:
+        self.db_path = db_path or default_db_path()
+        if self.db_path != ":memory:":
+            parent = os.path.dirname(self.db_path)
+            if parent:
+                os.makedirs(parent, exist_ok=True)
+        self._ctx: Optional[_ActorContext] = None
+        self._epoch_seq = 0
+        self._lock = threading.Lock()
+        # check_same_thread=False is safe: every mutation path is serialized
+        # by self._lock, so the connection is never used concurrently even when
+        # callers drive the kernel from different threads (concurrency tests).
+        self._conn = sqlite3.connect(
+            self.db_path, isolation_level=None, check_same_thread=False
+        )
+        self._conn.execute("PRAGMA foreign_keys = ON")
+        self._conn.execute(f"PRAGMA busy_timeout = {int(busy_timeout_ms)}")
+        self._register_actor_functions()
+        self._migrate()
+
+    # -- trusted-service actor functions ---------------------------------- #
+
+    def _register_actor_functions(self) -> None:
+        c = self._conn
+        c.create_function("cp_actor_principal", 0, lambda: self._ctx.principal if self._ctx else None)
+        c.create_function("cp_actor_kind", 0, lambda: self._ctx.kind if self._ctx else None)
+        c.create_function("cp_operation_mode", 0, lambda: self._ctx.mode if self._ctx else None)
+        c.create_function("cp_service_session", 0, lambda: self._ctx.session if self._ctx else None)
+        c.create_function("cp_context_epoch", 0, self._fn_context_epoch)
+        # Trusted-service helper: folds present + non-expired + epoch-consistent
+        # into the read/re-read epoch equality of #822 §4.
+        c.create_function("cp_actor_context_valid", 0, self._fn_context_valid)
+
+    def _fn_context_epoch(self) -> Optional[int]:
+        if self._ctx is None or self._ctx.expired:
+            return None
+        return self._ctx.live_epoch
+
+    def _fn_context_valid(self) -> int:
+        ctx = self._ctx
+        if ctx is None or ctx.expired:
+            return 0
+        # read/re-read epoch equality: a context whose live epoch has drifted
+        # from the epoch it was bound to (a stale/replaced connection context)
+        # is not bound to the active transaction and fails closed.
+        if ctx.live_epoch != ctx.bound_epoch:
+            return 0
+        if ctx.principal is None:
+            return 0
+        if ctx.kind not in ACTOR_KINDS or ctx.mode not in OPERATION_MODES:
+            return 0
+        return 1
+
+    # -- context lifecycle ------------------------------------------------ #
+
+    @contextmanager
+    def actor_context(
+        self, principal: str, kind: str, mode: str, session: Optional[str] = None
+    ) -> Iterator[None]:
+        """Bind a trusted actor context for the duration of the block."""
+        prev = self._ctx
+        self._epoch_seq += 1
+        epoch = self._epoch_seq
+        self._ctx = _ActorContext(
+            principal=principal, kind=kind, mode=mode, session=session,
+            bound_epoch=epoch, live_epoch=epoch,
+        )
+        try:
+            yield
+        finally:
+            self._ctx = prev
+
+    def _clear_context(self) -> None:
+        self._ctx = None
+
+    # -- migration -------------------------------------------------------- #
+
+    def _migrate(self) -> None:
+        self._conn.executescript(_SCHEMA_SQL)
+        self._conn.execute(
+            "INSERT OR IGNORE INTO arch01_meta(key, value) VALUES ('schema_version', ?)",
+            (str(SCHEMA_VERSION),),
+        )
+        self._conn.execute(
+            "INSERT OR IGNORE INTO arch01_meta(key, value) VALUES "
+            "('architecture', 'ARCH-01 Slice A: atomic install + authority kernel (#822); "
+            "disabled by default until readiness checks pass')"
+        )
+
+    # -- introspection ---------------------------------------------------- #
+
+    def is_installed(self) -> bool:
+        row = self._conn.execute("SELECT COUNT(*) FROM install_state").fetchone()
+        return bool(row[0])
+
+    def active_grant_count(self) -> int:
+        row = self._conn.execute(
+            "SELECT active_count FROM platform_active_invariant WHERE id = 1"
+        ).fetchone()
+        return int(row[0]) if row else 0
+
+    def audit_events(self) -> list[str]:
+        return [
+            r[0]
+            for r in self._conn.execute(
+                "SELECT event FROM audit_records ORDER BY audit_id"
+            ).fetchall()
+        ]
+
+    def close(self) -> None:
+        self._conn.close()
+
+    # -- operations ------------------------------------------------------- #
+
+    def install_platform(
+        self,
+        installer_principal_id: str = "platform.installer",
+        *,
+        session: Optional[str] = None,
+    ) -> OperationResult:
+        """Single atomic install transaction (#822 §4/§7).
+
+        ``BEGIN IMMEDIATE`` serializes concurrent installs; the loser rechecks
+        the marker and returns ``ALREADY_INSTALLED``, or — if it never acquires
+        the write lock — ``CONCURRENT_INSTALLATION_LOST``. On any stage failure
+        the whole transaction rolls back leaving no partial rows (AC3/AC5).
+        """
+        now = _utc_now_iso()
+        with self._lock:
+            try:
+                self._conn.execute("BEGIN IMMEDIATE")
+            except sqlite3.OperationalError as exc:
+                if "locked" in str(exc).lower() or "busy" in str(exc).lower():
+                    return OperationResult(CONCURRENT_INSTALLATION_LOST, str(exc))
+                raise
+            try:
+                if self.is_installed():
+                    self._conn.execute("ROLLBACK")
+                    return OperationResult(ALREADY_INSTALLED, "install marker already present")
+
+                with self.actor_context(installer_principal_id, "installer", "install", session):
+                    c = self._conn
+                    # class -> installer principal (temporary NULL issuer)
+                    cur = c.execute(
+                        "INSERT INTO principal_equivalence_classes(created_at) VALUES (?)",
+                        (now,),
+                    )
+                    class_id = cur.lastrowid
+                    c.execute(
+                        "INSERT INTO principals"
+                        "(principal_id, actor_kind, current_class_id, issuer_id, registered_by, created_at) "
+                        "VALUES (?, 'installer', ?, NULL, ?, ?)",
+                        (installer_principal_id, class_id, installer_principal_id, now),
+                    )
+                    # distinguished operator-key issuer
+                    cur = c.execute(
+                        "INSERT INTO authoritative_issuers(issuer_kind, issuer_ref, created_at) "
+                        "VALUES (?, ?, ?)",
+                        (DISTINGUISHED_ISSUER_KIND, DISTINGUISHED_ISSUER_ID, now),
+                    )
+                    issuer_id = cur.lastrowid
+                    # link installer -> issuer (permitted pre-marker)
+                    c.execute(
+                        "UPDATE principals SET issuer_id = ? WHERE principal_id = ?",
+                        (issuer_id, installer_principal_id),
+                    )
+                    # dominance tuples
+                    c.executemany(
+                        "INSERT INTO authority_dominance(dominant, subordinate) VALUES (?, ?)",
+                        DOMINANCE_TUPLES,
+                    )
+                    # seed
+                    c.execute(
+                        "INSERT INTO platform_bootstrap_seed(seed_id, installer_principal_id, created_at) "
+                        "VALUES (1, ?, ?)",
+                        (installer_principal_id, now),
+                    )
+                    # initial grant (granted_by NULL, active)
+                    c.execute(
+                        "INSERT INTO platform_bootstrap_grants"
+                        "(grantee_principal_id, granted_by, active, created_at) "
+                        "VALUES (?, NULL, 1, ?)",
+                        (installer_principal_id, now),
+                    )
+                    # active invariant
+                    c.execute(
+                        "INSERT INTO platform_active_invariant(id, active_count) VALUES (1, 1)"
+                    )
+                    # audit rows for the security-sensitive operation
+                    c.execute(
+                        "INSERT INTO audit_records(event, principal_id, detail, created_at) "
+                        "VALUES (?, ?, ?, ?)",
+                        (EVT_PRINCIPAL_REGISTERED, installer_principal_id, "installer", now),
+                    )
+                    c.execute(
+                        "INSERT INTO audit_records(event, principal_id, detail, created_at) "
+                        "VALUES (?, ?, ?, ?)",
+                        (EVT_GRANT_CREATED, installer_principal_id, "initial platform.bootstrap grant", now),
+                    )
+                    # install marker LAST -> fires the whole-bootstrap validator
+                    c.execute(
+                        "INSERT INTO install_state(id, marker, installed_at) VALUES (1, 'installed', ?)",
+                        (now,),
+                    )
+                    c.execute(
+                        "INSERT INTO audit_records(event, principal_id, detail, created_at) "
+                        "VALUES (?, ?, ?, ?)",
+                        (EVT_PLATFORM_INSTALLED, installer_principal_id, "platform installed", now),
+                    )
+                self._conn.execute("COMMIT")
+                return OperationResult(INSTALLED, "platform installed")
+            except sqlite3.Error as exc:
+                self._safe_rollback()
+                return OperationResult(self._classify(exc), str(exc))
+
+    def register_principal(
+        self,
+        principal_id: str,
+        actor_kind: str,
+        issuer_ref: str,
+        *,
+        actor_principal: str,
+        actor_kind_ctx: str = "operator",
+        session: Optional[str] = None,
+    ) -> OperationResult:
+        """Atomically create an equivalence class and its first principal.
+
+        The class is inserted *before* the principal, and ``current_class_id``
+        is ``NOT NULL`` (#822 AC6): a principal can never exist classless.
+        The principal references an existing issuer (non-NULL); the temporary
+        NULL-issuer exception is reserved for the installer during install
+        (AC7).
+        """
+        if actor_kind not in ACTOR_KINDS:
+            return OperationResult(INVALID_BOOTSTRAP_STATE, f"bad actor_kind {actor_kind!r}")
+        now = _utc_now_iso()
+        with self._lock:
+            try:
+                self._conn.execute("BEGIN IMMEDIATE")
+            except sqlite3.OperationalError as exc:
+                return OperationResult(AUTHORIZATION_DENIED, str(exc))
+            try:
+                if not self.is_installed():
+                    self._conn.execute("ROLLBACK")
+                    return OperationResult(INVALID_BOOTSTRAP_STATE, "platform not installed")
+                row = self._conn.execute(
+                    "SELECT issuer_id FROM authoritative_issuers WHERE issuer_ref = ?",
+                    (issuer_ref,),
+                ).fetchone()
+                if row is None:
+                    self._conn.execute("ROLLBACK")
+                    return OperationResult(INVALID_BOOTSTRAP_STATE, f"unknown issuer {issuer_ref!r}")
+                issuer_id = row[0]
+                with self.actor_context(actor_principal, actor_kind_ctx, "normal", session):
+                    cur = self._conn.execute(
+                        "INSERT INTO principal_equivalence_classes(created_at) VALUES (?)",
+                        (now,),
+                    )
+                    class_id = cur.lastrowid
+                    self._conn.execute(
+                        "INSERT INTO principals"
+                        "(principal_id, actor_kind, current_class_id, issuer_id, registered_by, created_at) "
+                        "VALUES (?, ?, ?, ?, ?, ?)",
+                        (principal_id, actor_kind, class_id, issuer_id, actor_principal, now),
+                    )
+                    self._conn.execute(
+                        "INSERT INTO audit_records(event, principal_id, detail, created_at) "
+                        "VALUES (?, ?, ?, ?)",
+                        (EVT_PRINCIPAL_REGISTERED, principal_id, actor_kind, now),
+                    )
+                self._conn.execute("COMMIT")
+                return OperationResult(INSTALLED, f"registered {principal_id}")
+            except sqlite3.Error as exc:
+                self._safe_rollback()
+                return OperationResult(self._classify(exc), str(exc))
+
+    def grant_platform_bootstrap(
+        self,
+        grantee_principal_id: str,
+        granted_by: str,
+        *,
+        actor_kind_ctx: str = "operator",
+        session: Optional[str] = None,
+    ) -> OperationResult:
+        """Create an additional active platform.bootstrap grant.
+
+        Serialized on the singleton invariant row via ``BEGIN IMMEDIATE``.
+        """
+        now = _utc_now_iso()
+        with self._lock:
+            try:
+                self._conn.execute("BEGIN IMMEDIATE")
+            except sqlite3.OperationalError as exc:
+                return OperationResult(AUTHORIZATION_DENIED, str(exc))
+            try:
+                if not self.is_installed():
+                    self._conn.execute("ROLLBACK")
+                    return OperationResult(INVALID_BOOTSTRAP_STATE, "platform not installed")
+                with self.actor_context(granted_by, actor_kind_ctx, "normal", session):
+                    self._conn.execute(
+                        "INSERT INTO platform_bootstrap_grants"
+                        "(grantee_principal_id, granted_by, active, created_at) "
+                        "VALUES (?, ?, 1, ?)",
+                        (grantee_principal_id, granted_by, now),
+                    )
+                    self._conn.execute(
+                        "UPDATE platform_active_invariant SET active_count = active_count + 1 WHERE id = 1"
+                    )
+                    self._conn.execute(
+                        "INSERT INTO audit_records(event, principal_id, detail, created_at) "
+                        "VALUES (?, ?, ?, ?)",
+                        (EVT_GRANT_CREATED, grantee_principal_id, f"granted_by={granted_by}", now),
+                    )
+                self._conn.execute("COMMIT")
+                return OperationResult(INSTALLED, f"granted to {grantee_principal_id}")
+            except sqlite3.Error as exc:
+                self._safe_rollback()
+                return OperationResult(self._classify(exc), str(exc))
+
+    def revoke_platform_bootstrap(
+        self,
+        grant_id: int,
+        *,
+        actor_principal: str,
+        actor_kind_ctx: str = "operator",
+        session: Optional[str] = None,
+    ) -> OperationResult:
+        """Revoke an active grant, floored so the last one can never drop.
+
+        The ``active_count >= 1`` CHECK plus ``BEGIN IMMEDIATE`` serialization
+        make two concurrent revocations unable to remove the final active grant
+        (#822 AC11): the decrement that would reach zero fails and rolls back.
+        """
+        now = _utc_now_iso()
+        with self._lock:
+            try:
+                self._conn.execute("BEGIN IMMEDIATE")
+            except sqlite3.OperationalError as exc:
+                return OperationResult(AUTHORIZATION_DENIED, str(exc))
+            try:
+                if not self.is_installed():
+                    self._conn.execute("ROLLBACK")
+                    return OperationResult(INVALID_BOOTSTRAP_STATE, "platform not installed")
+                row = self._conn.execute(
+                    "SELECT active, grantee_principal_id FROM platform_bootstrap_grants WHERE grant_id = ?",
+                    (grant_id,),
+                ).fetchone()
+                if row is None or row[0] != 1:
+                    self._conn.execute("ROLLBACK")
+                    return OperationResult(AUTHORIZATION_DENIED, "grant absent or already inactive")
+                grantee = row[1]
+                with self.actor_context(actor_principal, actor_kind_ctx, "normal", session):
+                    # Decrement first: the CHECK floor rejects dropping below 1,
+                    # aborting the whole revoke before the grant flips inactive.
+                    self._conn.execute(
+                        "UPDATE platform_active_invariant SET active_count = active_count - 1 WHERE id = 1"
+                    )
+                    self._conn.execute(
+                        "UPDATE platform_bootstrap_grants SET active = 0, revoked_at = ? WHERE grant_id = ?",
+                        (now, grant_id),
+                    )
+                    self._conn.execute(
+                        "INSERT INTO audit_records(event, principal_id, detail, created_at) "
+                        "VALUES (?, ?, ?, ?)",
+                        (EVT_GRANT_REVOKED, grantee, f"grant_id={grant_id}", now),
+                    )
+                self._conn.execute("COMMIT")
+                return OperationResult(INSTALLED, f"revoked grant {grant_id}")
+            except sqlite3.Error as exc:
+                self._safe_rollback()
+                return OperationResult(self._classify(exc), str(exc))
+
+    # -- helpers ---------------------------------------------------------- #
+
+    def _safe_rollback(self) -> None:
+        try:
+            self._conn.execute("ROLLBACK")
+        except sqlite3.Error:
+            pass
+
+    @staticmethod
+    def _classify(exc: sqlite3.Error) -> str:
+        msg = str(exc)
+        if "INVALID_ACTOR_CONTEXT" in msg:
+            return INVALID_ACTOR_CONTEXT
+        if "DOMINANCE_SET_MISMATCH" in msg:
+            return DOMINANCE_SET_MISMATCH
+        if "active_count" in msg or "CHECK constraint failed: platform_active_invariant" in msg:
+            # last-active-grant floor tripped
+            return AUTHORIZATION_DENIED
+        if any(tag in msg for tag in (
+            "INVALID_BOOTSTRAP_STATE", "IMMUTABLE_", "NOT_INSTALLED",
+        )):
+            return INVALID_BOOTSTRAP_STATE
+        return INVALID_BOOTSTRAP_STATE

tests/test_arch01_platform.py

@@ -0,0 +1,572 @@
+"""Executable acceptance tests for ARCH-01 Slice A (#822).
+
+Each acceptance criterion (#822 §12) and named test (#822 §13) is exercised
+against a real SQLite database. The migration runs on a fresh DB in ``setUp``;
+the test-run output is the durable evidence the issue requires (§14).
+
+Enforcement being proven:
+
+* ``[TRUSTED-SERVICE]`` — the ``cp_*`` actor functions exist only on the
+  trusted kernel connection; a raw connection cannot satisfy the triggers.
+* ``[SCHEMA]`` — fail-closed aborts, exact dominance set, NOT-NULL class,
+  immutability, and the last-active-grant floor are enforced by
+  CHECK/FK/trigger, verified here including raw-write bypass and concurrency.
+"""
+
+from __future__ import annotations
+
+import os
+import sqlite3
+import tempfile
+import threading
+import unittest
+from concurrent.futures import ThreadPoolExecutor
+
+import arch01_platform as ap
+from arch01_platform import (
+    ALREADY_INSTALLED,
+    AUTHORIZATION_DENIED,
+    CONCURRENT_INSTALLATION_LOST,
+    DISTINGUISHED_ISSUER_ID,
+    DOMINANCE_SET_MISMATCH,
+    DOMINANCE_TUPLES,
+    INSTALLED,
+    INVALID_ACTOR_CONTEXT,
+    INVALID_BOOTSTRAP_STATE,
+    PlatformKernel,
+)
+
+INSTALLER = "platform.installer"
+
+_BOOTSTRAP_TABLES = (
+    "principal_equivalence_classes",
+    "principals",
+    "authoritative_issuers",
+    "authority_dominance",
+    "platform_bootstrap_seed",
+    "platform_bootstrap_grants",
+    "platform_active_invariant",
+    "install_state",
+)
+
+
+def _count(kernel: PlatformKernel, table: str) -> int:
+    return kernel._conn.execute(f"SELECT COUNT(*) FROM {table}").fetchone()[0]
+
+
+def _count_where(kernel: PlatformKernel, table: str, where: str) -> int:
+    return kernel._conn.execute(f"SELECT COUNT(*) FROM {table} WHERE {where}").fetchone()[0]
+
+
+def _all_bootstrap_empty(kernel: PlatformKernel) -> bool:
+    return all(_count(kernel, t) == 0 for t in _BOOTSTRAP_TABLES)
+
+
+class Arch01MemoryTest(unittest.TestCase):
+    """Single-connection behavior on an in-memory database."""
+
+    def setUp(self) -> None:
+        self.kernel = PlatformKernel(":memory:")
+
+    def tearDown(self) -> None:
+        self.kernel.close()
+
+    # -- AC1 -------------------------------------------------------------- #
+    def test_install_clean(self) -> None:  # t_install_clean(+)
+        res = self.kernel.install_platform(INSTALLER)
+        self.assertEqual(res.code, INSTALLED)
+        self.assertTrue(self.kernel.is_installed())
+        self.assertEqual(_count(self.kernel, "install_state"), 1)
+        self.assertEqual(self.kernel.active_grant_count(), 1)
+        self.assertIn(ap.EVT_PLATFORM_INSTALLED, self.kernel.audit_events())
+        rows = set(
+            self.kernel._conn.execute(
+                "SELECT dominant, subordinate FROM authority_dominance"
+            ).fetchall()
+        )
+        self.assertEqual(rows, set(DOMINANCE_TUPLES))
+        issuer_ref = self.kernel._conn.execute(
+            "SELECT i.issuer_ref FROM principals p JOIN authoritative_issuers i "
+            "ON p.issuer_id = i.issuer_id WHERE p.principal_id = ?",
+            (INSTALLER,),
+        ).fetchone()
+        self.assertEqual(issuer_ref[0], DISTINGUISHED_ISSUER_ID)
+
+    # -- AC2 -------------------------------------------------------------- #
+    def test_install_twice(self) -> None:  # t_install_twice(-)
+        self.assertEqual(self.kernel.install_platform(INSTALLER).code, INSTALLED)
+        res2 = self.kernel.install_platform(INSTALLER)
+        self.assertEqual(res2.code, ALREADY_INSTALLED)
+        self.assertEqual(_count(self.kernel, "principals"), 1)
+        self.assertEqual(_count(self.kernel, "platform_bootstrap_grants"), 1)
+        self.assertEqual(_count(self.kernel, "install_state"), 1)
+
+    # -- AC3 / AC5 -------------------------------------------------------- #
+    def test_install_stage_rollback(self) -> None:  # t_install_stage_rollback
+        for stop in range(1, 9):
+            with self.subTest(stages=stop):
+                k = PlatformKernel(":memory:")
+                try:
+                    self._partial_bootstrap_then_rollback(k, stop)
+                    self.assertTrue(
+                        _all_bootstrap_empty(k),
+                        f"partial rows survived rollback at stage {stop}",
+                    )
+                    self.assertFalse(k.is_installed())
+                finally:
+                    k.close()
+
+    def test_no_partial_after_rollback(self) -> None:  # t_no_partial_after_rollback
+        k = PlatformKernel(":memory:")
+        try:
+            code = self._seed_bootstrap_and_mark(k, dominance=DOMINANCE_TUPLES[:-1])
+            self.assertEqual(code, DOMINANCE_SET_MISMATCH)
+            self.assertTrue(_all_bootstrap_empty(k))
+            self.assertFalse(k.is_installed())
+        finally:
+            k.close()
+
+    # -- AC4 -------------------------------------------------------------- #
+    def test_dominance_missing(self) -> None:  # t_dominance_missing(-)
+        k = PlatformKernel(":memory:")
+        try:
+            self.assertEqual(
+                self._seed_bootstrap_and_mark(k, dominance=DOMINANCE_TUPLES[:-1]),
+                DOMINANCE_SET_MISMATCH,
+            )
+            self.assertFalse(k.is_installed())
+        finally:
+            k.close()
+
+    def test_dominance_extra(self) -> None:  # t_dominance_extra(-)
+        k = PlatformKernel(":memory:")
+        try:
+            extra = DOMINANCE_TUPLES + (("platform.bootstrap", "rogue.extra"),)
+            self.assertEqual(
+                self._seed_bootstrap_and_mark(k, dominance=extra),
+                DOMINANCE_SET_MISMATCH,
+            )
+            self.assertFalse(k.is_installed())
+        finally:
+            k.close()
+
+    def test_dominance_malformed(self) -> None:  # t_dominance_malformed(-)
+        k = PlatformKernel(":memory:")
+        try:
+            malformed = DOMINANCE_TUPLES[:-1] + (("supervisor.root", "WRONG.subordinate"),)
+            self.assertEqual(
+                self._seed_bootstrap_and_mark(k, dominance=malformed),
+                DOMINANCE_SET_MISMATCH,
+            )
+            self.assertFalse(k.is_installed())
+        finally:
+            k.close()
+
+    # -- AC6 -------------------------------------------------------------- #
+    def test_principal_no_class(self) -> None:  # t_principal_no_class(-)
+        with self.kernel.actor_context("op", "operator", "install"):
+            with self.assertRaises(sqlite3.IntegrityError):
+                self.kernel._conn.execute(
+                    "INSERT INTO principals"
+                    "(principal_id, actor_kind, current_class_id, issuer_id, registered_by, created_at) "
+                    "VALUES ('x', 'operator', NULL, NULL, NULL, '2026-01-01T00:00:00Z')"
+                )
+
+    # -- AC7 -------------------------------------------------------------- #
+    def test_noninstaller_null_issuer(self) -> None:  # t_nonobstaller_null_issuer(-)
+        self.assertEqual(self.kernel.install_platform(INSTALLER).code, INSTALLED)
+        with self.kernel.actor_context("op", "operator", "normal"):
+            cur = self.kernel._conn.execute(
+                "INSERT INTO principal_equivalence_classes(created_at) VALUES ('2026-01-01T00:00:00Z')"
+            )
+            class_id = cur.lastrowid
+            with self.assertRaises(sqlite3.IntegrityError) as ctx:
+                self.kernel._conn.execute(
+                    "INSERT INTO principals"
+                    "(principal_id, actor_kind, current_class_id, issuer_id, registered_by, created_at) "
+                    "VALUES ('rogue', 'operator', ?, NULL, NULL, '2026-01-01T00:00:00Z')",
+                    (class_id,),
+                )
+            self.assertIn("INVALID_BOOTSTRAP_STATE", str(ctx.exception))
+
+    def test_installer_null_issuer_only_during_install(self) -> None:
+        self.assertEqual(self.kernel.install_platform(INSTALLER).code, INSTALLED)
+        with self.kernel.actor_context("i2", "installer", "install"):
+            cur = self.kernel._conn.execute(
+                "INSERT INTO principal_equivalence_classes(created_at) VALUES ('2026-01-01T00:00:00Z')"
+            )
+            class_id = cur.lastrowid
+            with self.assertRaises(sqlite3.IntegrityError):
+                self.kernel._conn.execute(
+                    "INSERT INTO principals"
+                    "(principal_id, actor_kind, current_class_id, issuer_id, registered_by, created_at) "
+                    "VALUES ('i2', 'installer', ?, NULL, NULL, '2026-01-01T00:00:00Z')",
+                    (class_id,),
+                )
+
+    # -- AC8 -------------------------------------------------------------- #
+    def test_context_missing(self) -> None:  # t_context_missing(-)
+        self.assertIsNone(self.kernel._ctx)
+        with self.assertRaises(sqlite3.IntegrityError) as ctx:
+            self.kernel._conn.execute(
+                "INSERT INTO principal_equivalence_classes(created_at) VALUES ('2026-01-01T00:00:00Z')"
+            )
+        self.assertIn("INVALID_ACTOR_CONTEXT", str(ctx.exception))
+
+    def test_context_stale(self) -> None:  # t_context_stale(-)
+        with self.kernel.actor_context("op", "operator", "normal"):
+            self.kernel._ctx.expired = True
+            with self.assertRaises(sqlite3.IntegrityError) as ctx:
+                self.kernel._conn.execute(
+                    "INSERT INTO principal_equivalence_classes(created_at) VALUES ('2026-01-01T00:00:00Z')"
+                )
+            self.assertIn("INVALID_ACTOR_CONTEXT", str(ctx.exception))
+
+    def test_context_epoch_shift(self) -> None:  # t_context_epoch_shift(-)
+        with self.kernel.actor_context("op", "operator", "normal"):
+            self.kernel._ctx.live_epoch = self.kernel._ctx.bound_epoch + 99
+            with self.assertRaises(sqlite3.IntegrityError) as ctx:
+                self.kernel._conn.execute(
+                    "INSERT INTO principal_equivalence_classes(created_at) VALUES ('2026-01-01T00:00:00Z')"
+                )
+            self.assertIn("INVALID_ACTOR_CONTEXT", str(ctx.exception))
+
+    def test_bad_actor_kind_or_mode_rejected(self) -> None:
+        for kind, mode in (("intruder", "normal"), ("operator", "sabotage")):
+            with self.subTest(kind=kind, mode=mode):
+                with self.kernel.actor_context("op", kind, mode):
+                    with self.assertRaises(sqlite3.IntegrityError):
+                        self.kernel._conn.execute(
+                            "INSERT INTO principal_equivalence_classes(created_at) "
+                            "VALUES ('2026-01-01T00:00:00Z')"
+                        )
+
+    # -- AC9 -------------------------------------------------------------- #
+    def test_bootstrap_immutable_update(self) -> None:  # t_bootstrap_immutable_{update}
+        self.assertEqual(self.kernel.install_platform(INSTALLER).code, INSTALLED)
+        cases = [
+            ("UPDATE install_state SET installed_at = 'x' WHERE id = 1", "IMMUTABLE_INSTALL_STATE"),
+            ("UPDATE platform_bootstrap_seed SET created_at = 'x' WHERE seed_id = 1", "IMMUTABLE_SEED"),
+            ("UPDATE authority_dominance SET subordinate = 'x' WHERE dominant = 'supervisor.root'", "IMMUTABLE_DOMINANCE"),
+            (f"UPDATE authoritative_issuers SET issuer_ref = 'x' WHERE issuer_ref = '{DISTINGUISHED_ISSUER_ID}'", "IMMUTABLE_ISSUER"),
+            (f"UPDATE principals SET actor_kind = 'operator' WHERE principal_id = '{INSTALLER}'", "IMMUTABLE_PRINCIPAL"),
+        ]
+        for sql, tag in cases:
+            with self.subTest(sql=sql):
+                with self.kernel.actor_context("op", "operator", "normal"):
+                    with self.assertRaises(sqlite3.IntegrityError) as ctx:
+                        self.kernel._conn.execute(sql)
+                    self.assertIn(tag, str(ctx.exception))
+
+    def test_bootstrap_immutable_delete(self) -> None:  # t_bootstrap_immutable_{delete}
+        self.assertEqual(self.kernel.install_platform(INSTALLER).code, INSTALLED)
+        cases = [
+            ("DELETE FROM install_state WHERE id = 1", "IMMUTABLE_INSTALL_STATE"),
+            ("DELETE FROM platform_bootstrap_seed WHERE seed_id = 1", "IMMUTABLE_SEED"),
+            ("DELETE FROM authority_dominance", "IMMUTABLE_DOMINANCE"),
+            ("DELETE FROM authoritative_issuers", "IMMUTABLE_ISSUER"),
+            (f"DELETE FROM principals WHERE principal_id = '{INSTALLER}'", "IMMUTABLE_PRINCIPAL"),
+            ("DELETE FROM platform_bootstrap_grants", "IMMUTABLE_GRANT"),
+        ]
+        for sql, tag in cases:
+            with self.subTest(sql=sql):
+                with self.kernel.actor_context("op", "operator", "normal"):
+                    with self.assertRaises(sqlite3.IntegrityError) as ctx:
+                        self.kernel._conn.execute(sql)
+                    self.assertIn(tag, str(ctx.exception))
+
+    def test_grant_reactivation_rejected(self) -> None:
+        self.assertEqual(self.kernel.install_platform(INSTALLER).code, INSTALLED)
+        self.kernel.register_principal(
+            "op1", "operator", DISTINGUISHED_ISSUER_ID, actor_principal=INSTALLER
+        )
+        self.assertEqual(
+            self.kernel.grant_platform_bootstrap("op1", INSTALLER).code, INSTALLED
+        )
+        gid = self.kernel._conn.execute(
+            "SELECT grant_id FROM platform_bootstrap_grants WHERE grantee_principal_id = 'op1'"
+        ).fetchone()[0]
+        self.assertEqual(
+            self.kernel.revoke_platform_bootstrap(gid, actor_principal=INSTALLER).code,
+            INSTALLED,
+        )
+        with self.kernel.actor_context("op", "operator", "normal"):
+            with self.assertRaises(sqlite3.IntegrityError) as ctx:
+                self.kernel._conn.execute(
+                    "UPDATE platform_bootstrap_grants SET active = 1 WHERE grant_id = ?",
+                    (gid,),
+                )
+            self.assertIn("IMMUTABLE_GRANT", str(ctx.exception))
+
+    # -- AC12 ------------------------------------------------------------- #
+    def test_raw_write_bypass(self) -> None:  # t_raw_write_bypass(raw-bypass)
+        with tempfile.TemporaryDirectory() as tmp:
+            path = os.path.join(tmp, "p.sqlite3")
+            k = PlatformKernel(path)
+            self.assertEqual(k.install_platform(INSTALLER).code, INSTALLED)
+            k.close()
+            raw = sqlite3.connect(path)
+            raw.execute("PRAGMA foreign_keys = ON")
+            try:
+                with self.assertRaises(sqlite3.Error):
+                    raw.execute(
+                        "INSERT INTO audit_records(event, created_at) "
+                        "VALUES ('forged', '2026-01-01T00:00:00Z')"
+                    )
+                    raw.commit()
+                with self.assertRaises(sqlite3.Error):
+                    raw.execute("UPDATE install_state SET installed_at = 'x' WHERE id = 1")
+                    raw.commit()
+                with self.assertRaises(sqlite3.Error):
+                    raw.execute("DELETE FROM platform_bootstrap_grants")
+                    raw.commit()
+            finally:
+                raw.close()
+
+    # -- AC13 ------------------------------------------------------------- #
+    def test_audit_created(self) -> None:  # t_audit_created(+)
+        self.assertEqual(self.kernel.install_platform(INSTALLER).code, INSTALLED)
+        self.kernel.register_principal(
+            "op1", "operator", DISTINGUISHED_ISSUER_ID, actor_principal=INSTALLER
+        )
+        self.assertEqual(
+            self.kernel.grant_platform_bootstrap("op1", INSTALLER).code, INSTALLED
+        )
+        gid = self.kernel._conn.execute(
+            "SELECT grant_id FROM platform_bootstrap_grants WHERE grantee_principal_id = 'op1'"
+        ).fetchone()[0]
+        self.assertEqual(
+            self.kernel.revoke_platform_bootstrap(gid, actor_principal=INSTALLER).code,
+            INSTALLED,
+        )
+        events = self.kernel.audit_events()
+        for evt in (
+            ap.EVT_PLATFORM_INSTALLED,
+            ap.EVT_GRANT_CREATED,
+            ap.EVT_GRANT_REVOKED,
+            ap.EVT_PRINCIPAL_REGISTERED,
+        ):
+            self.assertIn(evt, events)
+
+    # -- AC14 ------------------------------------------------------------- #
+    def test_audit_immutable(self) -> None:  # t_audit_immutable(raw-bypass)
+        self.assertEqual(self.kernel.install_platform(INSTALLER).code, INSTALLED)
+        with self.kernel.actor_context("op", "operator", "normal"):
+            with self.assertRaises(sqlite3.IntegrityError) as up:
+                self.kernel._conn.execute("UPDATE audit_records SET event = 'x' WHERE audit_id = 1")
+            self.assertIn("IMMUTABLE_AUDIT", str(up.exception))
+            with self.assertRaises(sqlite3.IntegrityError) as dl:
+                self.kernel._conn.execute("DELETE FROM audit_records WHERE audit_id = 1")
+            self.assertIn("IMMUTABLE_AUDIT", str(dl.exception))
+
+    # -- meta ------------------------------------------------------------- #
+    def test_schema_meta(self) -> None:
+        rows = dict(self.kernel._conn.execute("SELECT key, value FROM arch01_meta").fetchall())
+        self.assertEqual(rows["schema_version"], str(ap.SCHEMA_VERSION))
+        self.assertIn("disabled by default", rows["architecture"])
+
+    def test_register_principal_creates_class_first(self) -> None:
+        self.assertEqual(self.kernel.install_platform(INSTALLER).code, INSTALLED)
+        res = self.kernel.register_principal(
+            "svc1", "service", DISTINGUISHED_ISSUER_ID, actor_principal=INSTALLER
+        )
+        self.assertEqual(res.code, INSTALLED)
+        row = self.kernel._conn.execute(
+            "SELECT current_class_id FROM principals WHERE principal_id = 'svc1'"
+        ).fetchone()
+        self.assertIsNotNone(row[0])
+
+    # -- helpers ---------------------------------------------------------- #
+    def _partial_bootstrap_then_rollback(self, k: PlatformKernel, stop: int) -> None:
+        """Execute the first ``stop`` bootstrap statements, then ROLLBACK."""
+        now = "2026-01-01T00:00:00Z"
+        k._conn.execute("BEGIN IMMEDIATE")
+        class_id = None
+        issuer_id = None
+        try:
+            with k.actor_context(INSTALLER, "installer", "install"):
+                c = k._conn
+                if stop >= 1:
+                    class_id = c.execute(
+                        "INSERT INTO principal_equivalence_classes(created_at) VALUES (?)", (now,)
+                    ).lastrowid
+                if stop >= 2:
+                    c.execute(
+                        "INSERT INTO principals(principal_id, actor_kind, current_class_id, issuer_id, registered_by, created_at) "
+                        "VALUES (?, 'installer', ?, NULL, ?, ?)",
+                        (INSTALLER, class_id, INSTALLER, now),
+                    )
+                if stop >= 3:
+                    issuer_id = c.execute(
+                        "INSERT INTO authoritative_issuers(issuer_kind, issuer_ref, created_at) VALUES ('operator-key', ?, ?)",
+                        (DISTINGUISHED_ISSUER_ID, now),
+                    ).lastrowid
+                if stop >= 4:
+                    c.execute(
+                        "UPDATE principals SET issuer_id = ? WHERE principal_id = ?",
+                        (issuer_id, INSTALLER),
+                    )
+                if stop >= 5:
+                    c.executemany(
+                        "INSERT INTO authority_dominance(dominant, subordinate) VALUES (?, ?)",
+                        DOMINANCE_TUPLES,
+                    )
+                if stop >= 6:
+                    c.execute(
+                        "INSERT INTO platform_bootstrap_seed(seed_id, installer_principal_id, created_at) VALUES (1, ?, ?)",
+                        (INSTALLER, now),
+                    )
+                if stop >= 7:
+                    c.execute(
+                        "INSERT INTO platform_bootstrap_grants(grantee_principal_id, granted_by, active, created_at) VALUES (?, NULL, 1, ?)",
+                        (INSTALLER, now),
+                    )
+                if stop >= 8:
+                    c.execute("INSERT INTO platform_active_invariant(id, active_count) VALUES (1, 1)")
+        finally:
+            k._conn.execute("ROLLBACK")
+
+    def _seed_bootstrap_and_mark(self, k: PlatformKernel, dominance) -> str:
+        """Seed a full bootstrap with a caller-supplied dominance set, then
+        attempt the marker insert. Returns the classified failure code (or
+        INSTALLED). Rolls back on failure so no partial rows remain."""
+        now = "2026-01-01T00:00:00Z"
+        k._conn.execute("BEGIN IMMEDIATE")
+        try:
+            with k.actor_context(INSTALLER, "installer", "install"):
+                c = k._conn
+                class_id = c.execute(
+                    "INSERT INTO principal_equivalence_classes(created_at) VALUES (?)", (now,)
+                ).lastrowid
+                c.execute(
+                    "INSERT INTO principals(principal_id, actor_kind, current_class_id, issuer_id, registered_by, created_at) "
+                    "VALUES (?, 'installer', ?, NULL, ?, ?)",
+                    (INSTALLER, class_id, INSTALLER, now),
+                )
+                issuer_id = c.execute(
+                    "INSERT INTO authoritative_issuers(issuer_kind, issuer_ref, created_at) VALUES ('operator-key', ?, ?)",
+                    (DISTINGUISHED_ISSUER_ID, now),
+                ).lastrowid
+                c.execute(
+                    "UPDATE principals SET issuer_id = ? WHERE principal_id = ?",
+                    (issuer_id, INSTALLER),
+                )
+                c.executemany(
+                    "INSERT INTO authority_dominance(dominant, subordinate) VALUES (?, ?)",
+                    dominance,
+                )
+                c.execute(
+                    "INSERT INTO platform_bootstrap_seed(seed_id, installer_principal_id, created_at) VALUES (1, ?, ?)",
+                    (INSTALLER, now),
+                )
+                c.execute(
+                    "INSERT INTO platform_bootstrap_grants(grantee_principal_id, granted_by, active, created_at) VALUES (?, NULL, 1, ?)",
+                    (INSTALLER, now),
+                )
+                c.execute("INSERT INTO platform_active_invariant(id, active_count) VALUES (1, 1)")
+                c.execute(
+                    "INSERT INTO install_state(id, marker, installed_at) VALUES (1, 'installed', ?)",
+                    (now,),
+                )
+            k._conn.execute("COMMIT")
+            return INSTALLED
+        except sqlite3.Error as exc:
+            k._safe_rollback()
+            return PlatformKernel._classify(exc)
+
+
+class Arch01ConcurrencyTest(unittest.TestCase):
+    """Concurrency invariants require file-backed DBs and independent connections."""
+
+    def setUp(self) -> None:
+        self._tmp = tempfile.TemporaryDirectory()
+        self.path = os.path.join(self._tmp.name, "p.sqlite3")
+
+    def tearDown(self) -> None:
+        self._tmp.cleanup()
+
+    # -- AC10 ------------------------------------------------------------- #
+    def test_concurrent_install(self) -> None:  # t_concurrent_install(concurrency)
+        k1 = PlatformKernel(self.path, busy_timeout_ms=0)
+        k2 = PlatformKernel(self.path, busy_timeout_ms=0)
+        barrier = threading.Barrier(2)
+        results = {}
+
+        def _install(name, kernel):
+            barrier.wait()
+            results[name] = kernel.install_platform(INSTALLER).code
+
+        try:
+            with ThreadPoolExecutor(max_workers=2) as ex:
+                f1 = ex.submit(_install, "a", k1)
+                f2 = ex.submit(_install, "b", k2)
+                f1.result()
+                f2.result()
+            codes = sorted(results.values())
+            self.assertEqual(codes.count(INSTALLED), 1, f"exactly one install expected: {results}")
+            other = [c for c in results.values() if c != INSTALLED][0]
+            self.assertIn(other, (ALREADY_INSTALLED, CONCURRENT_INSTALLATION_LOST))
+            self.assertTrue(k1.is_installed())
+            self.assertEqual(_count(k1, "install_state"), 1)
+            self.assertEqual(_count(k1, "principals"), 1)
+        finally:
+            k1.close()
+            k2.close()
+
+    # -- AC11 ------------------------------------------------------------- #
+    def test_concurrent_last_grant_revoke(self) -> None:  # t_concurrent_last_grant_revoke
+        setup = PlatformKernel(self.path)
+        self.assertEqual(setup.install_platform(INSTALLER).code, INSTALLED)
+        setup.register_principal("op1", "operator", DISTINGUISHED_ISSUER_ID, actor_principal=INSTALLER)
+        self.assertEqual(setup.grant_platform_bootstrap("op1", INSTALLER).code, INSTALLED)
+        self.assertEqual(setup.active_grant_count(), 2)
+        gids = [
+            r[0]
+            for r in setup._conn.execute(
+                "SELECT grant_id FROM platform_bootstrap_grants WHERE active = 1 ORDER BY grant_id"
+            ).fetchall()
+        ]
+        setup.close()
+        self.assertEqual(len(gids), 2)
+
+        k1 = PlatformKernel(self.path, busy_timeout_ms=3000)
+        k2 = PlatformKernel(self.path, busy_timeout_ms=3000)
+        barrier = threading.Barrier(2)
+        results = {}
+
+        def _revoke(name, kernel, gid):
+            barrier.wait()
+            results[name] = kernel.revoke_platform_bootstrap(gid, actor_principal=INSTALLER).code
+
+        try:
+            with ThreadPoolExecutor(max_workers=2) as ex:
+                f1 = ex.submit(_revoke, "a", k1, gids[0])
+                f2 = ex.submit(_revoke, "b", k2, gids[1])
+                f1.result()
+                f2.result()
+            codes = list(results.values())
+            self.assertEqual(codes.count(INSTALLED), 1, f"exactly one revoke should win: {results}")
+            self.assertEqual(codes.count(AUTHORIZATION_DENIED), 1, f"one revoke must be denied: {results}")
+            self.assertEqual(k1.active_grant_count(), 1)
+            self.assertEqual(_count_where(k1, "platform_bootstrap_grants", "active = 1"), 1)
+        finally:
+            k1.close()
+            k2.close()
+
+    def test_revoke_final_grant_denied(self) -> None:
+        k = PlatformKernel(self.path)
+        try:
+            self.assertEqual(k.install_platform(INSTALLER).code, INSTALLED)
+            gid = k._conn.execute(
+                "SELECT grant_id FROM platform_bootstrap_grants WHERE active = 1"
+            ).fetchone()[0]
+            res = k.revoke_platform_bootstrap(gid, actor_principal=INSTALLER)
+            self.assertEqual(res.code, AUTHORIZATION_DENIED)
+            self.assertEqual(k.active_grant_count(), 1)
+            self.assertEqual(_count_where(k, "platform_bootstrap_grants", "active = 1"), 1)
+        finally:
+            k.close()
+
+
+if __name__ == "__main__":
+    unittest.main()