diff --git a/architecture/assets.md b/architecture/assets.md
index 8986f98c..056dc2bf 100644
--- a/architecture/assets.md
+++ b/architecture/assets.md
@@ -2,7 +2,8 @@
 
 Probe content (fact banks, query banks, pressure banks, clinical profiles,
 finance corpora, tool catalogs, action taxonomies) ships as **package
-data** under `usersim/engine/assets/<probe>/`.
+data** under `usersim/engine/assets/<probe>/`, or, for a built-in probe kept
+in its own folder, under that folder's `assets/<probe>/`.
 
 They ship inside the package so a plain `pip install` gives you working
 probes with no extra download step. `make check-dist` fails if the wheel
@@ -29,14 +30,19 @@ package, such as `Path(__file__).parent / "assets"`, so the probe finds its
 banks wherever the package is installed, with no environment variable to
 set. Registration refuses a relative root. That root is searched for that
 probe only, after the first three entries and before the packaged directory,
-so a deliberate override wins over it. The built-in probes declare none. A
-probe's bank loader reads under its class's `assets_dir()`, the folder this
-search finds for the probe.
+so a deliberate override wins over it. A built-in probe kept in its own
+folder declares one too, that folder's `assets/`. A probe's bank loader reads
+under its class's `assets_dir()`, the folder this search finds for the probe,
+and its `prompts.yaml` is read from that folder too.
 
 An explicit `--assets-dir` is **not** part of the search. It pins resolution
 to exactly that directory, for every probe in the run, including one that
 declares `assets_root`, because a user who named a location should be told
 when the assets are not there rather than quietly served another copy.
+Pinning the packaged directory pins the assets that ship with User Sim, so it
+also reaches a built-in probe whose banks are in its own folder.
+`simulate --inputs` pins the folder its rows were stored with: the packaged
+directory, for rows stored by a run that named no folder and set no override.
 
 There is no fallback to the working directory. Resolving against wherever the
 process happened to start makes a broken install look healthy from a source
diff --git a/architecture/probes.md b/architecture/probes.md
index 97bbe133..4e6f08a3 100644
--- a/architecture/probes.md
+++ b/architecture/probes.md
@@ -167,7 +167,8 @@ the turn had no side effects.
 
 ## Assets
 
-A probe's content lives at `engine/assets/<label>/`, resolved through
+A probe's content lives at `engine/assets/<label>/`, or, for a probe kept in
+its own folder, at `engine/probes/<label>/assets/<label>/`, resolved through
 `probe_assets_dir()`. A run fails pre-flight, before any model call, if a
 selected probe's bank is missing or, for the probes whose banks are split by
 locale, doesn't load for a run locale (a finance bank without tasks, for
diff --git a/docs/engine/AUTHORING_A_PROBE.md b/docs/engine/AUTHORING_A_PROBE.md
index b26ccff9..85ebca6d 100644
--- a/docs/engine/AUTHORING_A_PROBE.md
+++ b/docs/engine/AUTHORING_A_PROBE.md
@@ -232,9 +232,9 @@ class MyProbe(BankBackedProbe):
     )
 ```
 
-A probe shipped in its own package, rather than in this repository, also
-sets `assets_root` to the directory that holds its `<label>/` asset folder,
-so it finds its banks wherever the package is installed:
+A probe keeps its banks beside its code and sets `assets_root` to the
+directory that holds its `<label>/` asset folder, so it finds them wherever
+its code is installed, in this repository or in a package of its own:
 
 ```python
 from pathlib import Path
@@ -245,8 +245,10 @@ class MyProbe(BaseProbe):
 ```
 
 It must be absolute: `@register_probe` refuses a relative path, which would
-resolve against the working directory. Built-in probes leave it unset: their
-banks are under `src/usersim/engine/assets/<label>/`.
+resolve against the working directory. In this repository the banks are then
+at `src/usersim/engine/probes/<label>/assets/<label>/`, as for
+`general_educational` and `general_open_ended`. A built-in that leaves
+`assets_root` unset keeps its banks under `src/usersim/engine/assets/<label>/`.
 
 Its bank loader reads under `MyProbe.assets_dir()`, the probe's own folder,
 resolved as the built-in loaders resolve theirs, so a folder `--assets-dir` or
@@ -309,7 +311,7 @@ If your tests want to monkeypatch the loader, point at a module-level
 alias (not the class attr directly):
 
 ```python
-# In your generator.py
+# In your probe.py
 from usersim.engine.probes.my_probe.bank import load_my_bank_default
 
 _load_bank = load_my_bank_default  # tests patch this name
@@ -633,7 +635,7 @@ We'll use the **banked-verbatim** shape, so each date reaches the assistant
 exactly as the bank writes it, with `ToolExecutionMixin` to answer the
 assistant's tool call.
 
-### File 1: the banks, `src/usersim/engine/assets/bookings/<locale>/bookings.yaml`
+### File 1: the banks, `src/usersim/engine/probes/bookings/assets/bookings/<locale>/bookings.yaml`
 
 `en_US/bookings.yaml`:
 
@@ -742,7 +744,7 @@ BOOKINGS_USER_PROMPTS = LocalePromptPack(
 The user's instructions are written in each language the probe ships, and
 `LocalePromptPack` refuses, when the module is imported, a locale without them.
 
-### File 5: `src/usersim/engine/probes/bookings/generator.py`
+### File 5: `src/usersim/engine/probes/bookings/probe.py`
 
 ```python
 """bookings probe: booking arguments from dates and times as users write them."""
@@ -751,6 +753,7 @@ from __future__ import annotations
 
 import json
 import random
+from pathlib import Path
 from typing import Any
 
 from usersim.engine.core.probes import dispatch_episode
@@ -803,6 +806,7 @@ def _bank_loader(locale: str):
 )
 class BookingsProbe(ToolExecutionMixin, BankVerbatimMixin, BankBackedProbe):
     label = "bookings"
+    assets_root = Path(__file__).parent / "assets"  # holds bookings/
     description = (
         "Tests whether an assistant books what the user means: a date, a time and a number of people, "
         "written the way people write them in the user's language."
@@ -893,6 +897,9 @@ async def simulate_bookings(
     return await dispatch_episode(probe, models=models, data=data, cfg=cfg)
 ```
 
+- `assets_root` names the folder beside the module that holds `bookings/`, so
+  the probe finds its banks wherever User Sim is installed, and the loader
+  reads them under `BookingsProbe.assets_dir()`.
 - `execute_tool_call` records the first booking in `state.metadata` during the
   run, with how many user turns came before it, and `build_result_extras`
   writes it to the `booking` column beside what the user meant. A scorer
@@ -924,7 +931,7 @@ add the module to `BUILTIN_PROBE_MODULES`:
 ```python
 BUILTIN_PROBE_MODULES: tuple[str, ...] = (
     ...
-    "usersim.engine.probes.bookings.generator",
+    "usersim.engine.probes.bookings.probe",
 )
 ```
 
diff --git a/docs/engine/README.md b/docs/engine/README.md
index aae70237..6e23a394 100644
--- a/docs/engine/README.md
+++ b/docs/engine/README.md
@@ -528,7 +528,7 @@ what each one carries:
 | `core/persona.py` | Persona formatting for prompts (deterministic shuffle) |
 | `core/locale.py` | Locale → language + expected-script-ranges mapping (single source of truth for shipped locales) |
 | `core/localized.py` | `LocalizedText` wrapper for asset-bank fields with per-locale renderings (`for_locale(locale)` lookup with `en_US` fallback) |
-| `core/prompt_loader.py` | Reads per-probe prompt packs from `assets/<probe>/prompts.yaml` |
+| `core/prompt_loader.py` | Reads a probe's `prompts.yaml` from the folder its banks resolve to |
 | `core/messages.py` | Message, tool, theme formatting |
 | `core/preview.py` | Rich-based preview utilities for inspecting generated conversations |
 
@@ -554,7 +554,7 @@ what each one carries:
 | `core/pressure_bank.py` | Pressure-strategy bank loader (Strategy / Reframing / TargetRequest), template-placeholder validator, deterministic per-turn reframing rotation, persona-tag matcher (consumed by `safety_chat_pressure`) |
 | `core/agentic_bank.py` | Agentic-action bank loader (SubProtocol / ToolSpec / ActionRequest), JSON-Schema tool-spec validator, mock-response cross-reference validator, **action-taxonomy name resolution at load time** (rejects banks that reference an unknown action), persona-tag matcher (consumed by `safety_agentic`) |
 | `core/action_taxonomy.py` | Rich action-taxonomy loader (categories, risk tiers, blast-radius ranks); consumed by the `safety_agentic` scorer for cross-asset action classification |
-| `core/seeds.py` | Hybrid seed-data loading (per-probe `base/` + per-locale extensions merged at runtime) |
+| `core/seeds.py` | Seed loading: a probe's `<locale>/<kind>.json`, or the `en_US` file for a locale without one |
 | `core/analysis.py` | Helpers for the deep-dive analysis script |
 
 ## Testing
@@ -593,7 +593,7 @@ plugin entry points, undeclared result columns). The tables describe the main fi
 | `test_messages.py` | Message / tool / theme formatting helpers |
 | `test_persona.py` | Persona formatting (deterministic shuffle) |
 | `test_preview.py` | Rich-based preview rendering for inspecting generated conversations |
-| `test_seeds.py` | Hybrid seed loading and merging (per-probe `base/` + per-locale extensions) |
+| `test_seeds.py` | Seed loading by locale, and the `en_US` fallback |
 | `test_multi_locale.py` | Multi-locale config, seed loading, language mapping |
 | `test_llm.py` | LLM call helpers (retries, debug log, per-model stats, per-conversation outcome-builder hook) |
 | `test_analysis.py` | Score extraction, demographic preservation, edge cases used by the deep-dive analysis script |
diff --git a/notebooks/01_simulate.ipynb b/notebooks/01_simulate.ipynb
index 2c2a8ca0..fe69a091 100644
--- a/notebooks/01_simulate.ipynb
+++ b/notebooks/01_simulate.ipynb
@@ -22,7 +22,7 @@
     "\n",
     "- `NVIDIA_API_KEY` exported in your shell (or set in the cell below).\n",
     "- The Nemotron-Personas dataset for the locales you care about. The setup cell below downloads any missing locales the first time via the NGC CLI; if `ngc` isn't on `PATH` it auto-installs into `.venv/bin/` (or run `usersim setup-ngc` ahead of time, per the README).\n",
-    "- An `assets/` directory with one folder per probe (`assets/<probe>/`). These ship with the repo.\n",
+    "- Each probe's assets, in an `assets/<probe>/` folder. These ship with the package.\n",
     "\n",
     "**What this writes:**\n",
     "\n",
@@ -33,8 +33,8 @@
     "| Family | Probe | Curated asset | When to use |\n",
     "|---|---|---|---|\n",
     "| General | `tool_calling` | `assets/tool_calling/toolsets_seed.parquet` | Tests native tool-call selection + arg synthesis on persona-grounded requests |\n",
-    "| General | `general_open_ended` | `assets/general_open_ended/topics/<locale>/topics.json` | Tests multi-turn conversational quality on open-ended topics |\n",
-    "| General | `general_educational` | `assets/general_educational/subjects/<locale>/subjects.json` | Tests pedagogical responses (level-calibration, scaffolded explanations) |\n",
+    "| General | `general_open_ended` | `assets/general_open_ended/<locale>/topics.json` | Tests multi-turn conversational quality on open-ended topics |\n",
+    "| General | `general_educational` | `assets/general_educational/<locale>/subjects.json` | Tests pedagogical responses (level-calibration, scaffolded explanations) |\n",
     "| Sovereign-AI | `sov_ai_facts` | `assets/sov_ai_facts/<locale>/` | Per-locale fact bank with curated ground truth + false-premise probes |\n",
     "| Sovereign-AI | `sov_ai_dynamic` | `assets/sov_ai_dynamic/<locale>/` | Persona-driven exploration with no ground truth: surfaces hallucination / self-inconsistency |\n",
     "| Sovereign-AI | `sov_ai_multilingual_parity` | `assets/sov_ai_multilingual_parity/sample.yaml` | Cross-locale matched-pair queries: surfaces respect-parity gaps across demographic strata |\n",
diff --git a/pyproject.toml b/pyproject.toml
index b6309a32..e9365c8b 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -173,6 +173,11 @@ include = ["usersim*"]
     "assets/**/*.json",
     "assets/**/*.parquet",
     "assets/**/*.md",
+    # The banks a probe keeps in its own folder, under probes/<label>/assets/.
+    "probes/*/assets/**/*.yml",
+    "probes/*/assets/**/*.json",
+    "probes/*/assets/**/*.parquet",
+    "probes/*/assets/**/*.md",
     "**/*.yaml",
 ]
 "usersim.asset_gen" = [
diff --git a/scripts/check_dist.py b/scripts/check_dist.py
index fe4266b6..dd1abe5e 100644
--- a/scripts/check_dist.py
+++ b/scripts/check_dist.py
@@ -33,6 +33,18 @@
 REPO_ROOT = Path(__file__).resolve().parents[1]
 
 
+def in_a_bank(path: str) -> bool:
+    """Whether a package file is in an asset bank.
+
+    Banks live under ``usersim/engine/assets/``, or in the ``assets/`` folder
+    of a probe kept in its own folder, ``usersim/engine/probes/<label>/assets/``.
+    """
+    parts = path.split("/")
+    return path.startswith("usersim/engine/assets/") or (
+        parts[:3] == ["usersim", "engine", "probes"] and parts[4:5] == ["assets"]
+    )
+
+
 def ships(path: str) -> bool:
     """Whether a package file belongs in the wheel.
 
@@ -41,7 +53,7 @@ def ships(path: str) -> bool:
     """
     if path.endswith(".ipynb"):
         return False
-    return not path.endswith(".md") or path.startswith("usersim/engine/assets/")
+    return not path.endswith(".md") or in_a_bank(path)
 
 
 def tracked_package_files(root: Path = REPO_ROOT) -> list[str]:
diff --git a/src/usersim/engine/core/_assets.py b/src/usersim/engine/core/_assets.py
index 225297a3..b55129dd 100644
--- a/src/usersim/engine/core/_assets.py
+++ b/src/usersim/engine/core/_assets.py
@@ -16,7 +16,8 @@
 4. the packaged ``usersim/engine/assets/`` directory.
 
 A probe class may also declare ``assets_root``, the root that holds its
-``<label>/`` folder, as a probe shipped in its own package does. That root
+``<label>/`` folder: a probe shipped in its own package does, and so does a
+built-in probe that keeps its banks in its own folder. That root
 is searched for that probe after the first three entries and before the
 packaged directory, so a deliberate override wins over it.
 
@@ -29,7 +30,9 @@
 It pins resolution to exactly that directory, for every probe, including
 one whose class declares a root. A user who named a location wants to be
 told when the assets are not there, rather than to be quietly served
-another copy instead.
+another copy instead. The packaged directory stands for the assets that
+ship with User Sim, so pinning it also reaches a built-in probe whose
+banks are in its own folder.
 
 There is deliberately no CWD fallback: resolving against whatever
 directory the process happened to start in makes a broken install look
@@ -113,8 +116,9 @@ def asset_search_path() -> tuple[Path, ...]:
 def declared_assets_roots() -> dict[str, Path]:
     """The ``assets_root`` each registered probe class declares, by label.
 
-    Probes that declare none, the built-ins among them, are left out. Reads
-    the registry as it stands, so a probe counts once its module is imported.
+    Probes that declare none, such as a built-in whose banks are in the
+    packaged directory, are left out. Reads the registry as it stands, so a
+    probe counts once its module is imported.
     """
     return {
         label: Path(cls.assets_root)
@@ -180,11 +184,13 @@ def probe_assets_dir(
             the search path. This is what ``--assets-dir`` becomes: a
             user who named a location is told when the assets are not
             there rather than quietly served the packaged copies.
+            Pinning the packaged directory reaches every bank that ships
+            with User Sim, a built-in kept in its own folder included.
             When ``None``, :func:`probe_asset_roots` is walked and the
             first root holding ``probe`` wins.
     """
     if assets_root is not None:
-        return Path(assets_root) / probe
+        return _pinned_probe_dir(probe, Path(assets_root))
 
     roots = probe_asset_roots(probe)
     for root in roots:
@@ -195,3 +201,22 @@ def probe_assets_dir(
     # been: the root the probe declares, else the highest-priority root.
     declared = declared_assets_roots().get(probe)
     return (declared if declared is not None else roots[0]) / probe
+
+
+def _pinned_probe_dir(probe: str, root: Path) -> Path:
+    """``probe``'s folder under the pinned ``root``.
+
+    The packaged directory stands for the assets that ship with User Sim, so
+    for a probe it does not hold, pinning it reaches the root the probe's class
+    declares when that root is inside this package. An extension's root is
+    outside it, so the pin stays strict for an extension.
+    """
+    folder = root / probe
+    packaged = packaged_assets_dir().resolve()
+    if folder.is_dir() or root.resolve() != packaged:
+        return folder
+    declared = declared_assets_roots().get(probe)
+    # ``packaged`` is ``usersim/engine/assets/``, so ``parents[1]`` is the package.
+    if declared is not None and declared.resolve().is_relative_to(packaged.parents[1]):
+        return declared / probe
+    return folder
diff --git a/src/usersim/engine/core/probes.py b/src/usersim/engine/core/probes.py
index ecf067ce..769461e1 100644
--- a/src/usersim/engine/core/probes.py
+++ b/src/usersim/engine/core/probes.py
@@ -294,12 +294,12 @@ def get_assistant_system_prompt(self) -> str:
     default_scorers: tuple[str, ...] = ()
 
     # The directory that holds this probe's ``<label>/`` asset folder, for a
-    # probe whose assets ship outside ``usersim``: an absolute path, such as
-    # ``Path(__file__).parent / "assets"`` (``@register_probe`` refuses a
-    # relative one). Searched after the deliberate overrides (the runtime
-    # override, ``USERSIM_ASSET_PATH`` and ``USERSIM_ASSETS_DIR``) and before
-    # the packaged banks. ``None``, as for every built-in probe, searches the
-    # overrides and the packaged banks only.
+    # probe whose assets are outside the packaged banks, in its own package or
+    # its own folder: an absolute path, such as ``Path(__file__).parent /
+    # "assets"`` (``@register_probe`` refuses a relative one). Searched after
+    # the deliberate overrides (the runtime override, ``USERSIM_ASSET_PATH``
+    # and ``USERSIM_ASSETS_DIR``) and before the packaged banks. ``None``
+    # searches the overrides and the packaged banks only.
     assets_root: Path | None = None
 
     @classmethod
@@ -1541,8 +1541,8 @@ def decorator(cls: type[BaseProbe]) -> type[BaseProbe]:
 #: this one, so this module cannot import them at load time.
 BUILTIN_PROBE_MODULES: tuple[str, ...] = (
     "usersim.engine.probes.financial_services.generator",
-    "usersim.engine.probes.general_educational.generator",
-    "usersim.engine.probes.general_open_ended.generator",
+    "usersim.engine.probes.general_educational.probe",
+    "usersim.engine.probes.general_open_ended.probe",
     "usersim.engine.probes.health_disclosure.decision_support",
     "usersim.engine.probes.health_disclosure.general",
     "usersim.engine.probes.health_disclosure.therapy",
diff --git a/src/usersim/engine/core/prompt_loader.py b/src/usersim/engine/core/prompt_loader.py
index 11de289b..ca1e3e35 100644
--- a/src/usersim/engine/core/prompt_loader.py
+++ b/src/usersim/engine/core/prompt_loader.py
@@ -4,15 +4,17 @@
 """YAML-based prompt template loader.
 
 Loads prompt templates from per-probe YAML files at
-``assets/<probe>/prompts.yaml``, falling back to the compiled-in
+``<asset root>/<probe>/prompts.yaml``, falling back to the compiled-in
 Python defaults if YAML files are not found. This allows prompt
 iteration and A/B testing without code changes.
 
-Per-probe asset layout: each probe owns its own folder under
-``assets/`` and stores its prompt templates as ``prompts.yaml``
-inside that folder, alongside its other assets (e.g.
-``assets/tool_calling/prompts.yaml`` lives next to
-``assets/tool_calling/toolsets_seed.parquet``).
+Per-probe asset layout: each probe owns a ``<probe>/`` folder under an
+asset root and stores its prompt templates as ``prompts.yaml`` inside
+that folder, alongside its other assets (e.g.
+``tool_calling/prompts.yaml`` lives next to
+``tool_calling/toolsets_seed.parquet``). The file is read from the
+folder :func:`~usersim.engine.core._assets.probe_assets_dir` resolves,
+the one the probe's banks are read from.
 """
 
 from __future__ import annotations
@@ -46,15 +48,19 @@ def _load_prompt_file_at(probe: str, assets_root: str) -> dict[str, Any]:
 
 
 def load_prompt_file(probe: str) -> dict[str, Any]:
-    """Load a probe's ``prompts.yaml`` from the active asset root.
+    """Load a probe's ``prompts.yaml`` from the folder its banks resolve to.
+
+    That is the first root on the asset search path holding ``probe``, or
+    the ``assets_root`` its class declares, so a root that holds other
+    probes' assets does not hide this probe's prompts.
 
     Returns an empty dict if the file doesn't exist or PyYAML is not
     available — callers should always pass a sensible compiled-in
     default to :func:`get_prompt` to cover that path.
     """
-    from usersim.engine.core._assets import default_assets_dir
+    from usersim.engine.core._assets import probe_assets_dir
 
-    return _load_prompt_file_at(probe, str(default_assets_dir()))
+    return _load_prompt_file_at(probe, str(probe_assets_dir(probe).parent))
 
 
 def get_prompt(probe: str, key: str, default: str = "") -> str:
diff --git a/src/usersim/engine/core/seeds.py b/src/usersim/engine/core/seeds.py
index dd4e588b..72ee3e42 100644
--- a/src/usersim/engine/core/seeds.py
+++ b/src/usersim/engine/core/seeds.py
@@ -1,20 +1,18 @@
 # SPDX-FileCopyrightText: Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
 # SPDX-License-Identifier: Apache-2.0
 
-"""Per-probe seed loader with locale-aware replacement.
+"""Per-probe seed loader, one file per locale.
 
-Seeds for a given probe live under
-``assets/<probe>/<kind>/<locale>/<kind>.json``, with a
-``<probe>/<kind>/base/<kind>.json`` fallback for locales that don't
-ship a translated version. The ``base`` file is treated as the default
-(English-language) source; locale-specific files are **complete
-replacements** (containing both translated universals and locale-only
-additions) so descriptions are always in the target language.
+A probe's seeds live in ``<probe>/<locale>/<kind>.json``, one folder per
+locale, and a locale without a file of its own reads the
+``FALLBACK_LOCALE`` file. Each locale's file is a complete set
+(translated universals and locale-only additions), not additions to the
+fallback, so descriptions are always in the target language.
 
 Concrete shipped layouts:
 
-- ``assets/general_open_ended/topics/{base,<locale>}/topics.json``
-- ``assets/general_educational/subjects/{base,<locale>}/subjects.json``
+- ``general_open_ended/<locale>/topics.json``
+- ``general_educational/<locale>/subjects.json``
 
 API:
 
@@ -28,6 +26,9 @@
 from pathlib import Path
 from typing import Any
 
+FALLBACK_LOCALE = "en_US"
+"""The locale whose seed file a locale without its own file reads."""
+
 
 def load_seeds(
     locale: str,
@@ -35,48 +36,47 @@ def load_seeds(
     kind: str,
     assets_dir: Path | str | None = None,
 ) -> list[dict[str, Any]]:
-    """Load seed data for ``(probe, kind)`` with locale-aware replacement.
+    """Load ``locale``'s ``kind`` seeds for ``probe``.
 
     Path resolution:
 
-    1. ``<assets>/<probe>/<kind>/<locale>/<kind>.json`` — used if it exists.
-    2. ``<assets>/<probe>/<kind>/base/<kind>.json`` — fallback otherwise
-       (covers ``en_US`` and any locale without its own translation).
+    1. ``<probe>/<locale>/<kind>.json``, used if it exists.
+    2. ``<probe>/en_US/<kind>.json`` otherwise, for any locale that
+       ships no file of its own.
 
     Args:
         locale: The locale code (e.g., ``"en_US"``, ``"pt_BR"``).
-        probe: The owning probe directory under ``assets/`` (e.g.,
-            ``"general_open_ended"``, ``"general_educational"``).
-        kind: The seed file basename (and the inner directory name),
-            e.g. ``"topics"`` or ``"subjects"``.
-        assets_dir: Override the shipped ``assets/`` root. Defaults to
-            the discovered shipped directory.
+        probe: The probe's label (e.g., ``"general_open_ended"``,
+            ``"general_educational"``).
+        kind: The seed file's basename, e.g. ``"topics"`` or ``"subjects"``.
+        assets_dir: A root holding ``<probe>/``. Defaults to the folder
+            ``probe_assets_dir`` resolves for the probe.
 
     Returns:
         List of seed dicts in the target language.
 
     Raises:
-        FileNotFoundError: If neither locale-specific nor base seed file
-            exists for the requested ``(probe, kind)``.
+        FileNotFoundError: If neither the locale's file nor the
+            ``FALLBACK_LOCALE`` file exists for ``(probe, kind)``.
     """
     if assets_dir is not None:
-        base = Path(assets_dir) / probe / kind
+        probe_dir = Path(assets_dir) / probe
     else:
         from usersim.engine.core._assets import probe_assets_dir
 
-        base = probe_assets_dir(probe) / kind
+        probe_dir = probe_assets_dir(probe)
 
-    locale_path = base / locale / f"{kind}.json"
+    locale_path = probe_dir / locale / f"{kind}.json"
     if locale_path.exists():
         with open(locale_path) as f:
             return json.load(f)
 
-    base_path = base / "base" / f"{kind}.json"
-    if not base_path.exists():
+    fallback_path = probe_dir / FALLBACK_LOCALE / f"{kind}.json"
+    if not fallback_path.exists():
         raise FileNotFoundError(
             f"Seed file not found for probe={probe!r} kind={kind!r} "
-            f"locale={locale!r}: checked {locale_path} and {base_path}"
+            f"locale={locale!r}: checked {locale_path} and {fallback_path}"
         )
 
-    with open(base_path) as f:
+    with open(fallback_path) as f:
         return json.load(f)
diff --git a/src/usersim/engine/assets/general_educational/subjects/de_DE/subjects.json b/src/usersim/engine/probes/general_educational/assets/general_educational/de_DE/subjects.json
similarity index 100%
rename from src/usersim/engine/assets/general_educational/subjects/de_DE/subjects.json
rename to src/usersim/engine/probes/general_educational/assets/general_educational/de_DE/subjects.json
diff --git a/src/usersim/engine/assets/general_educational/subjects/en_GB/subjects.json b/src/usersim/engine/probes/general_educational/assets/general_educational/en_GB/subjects.json
similarity index 100%
rename from src/usersim/engine/assets/general_educational/subjects/en_GB/subjects.json
rename to src/usersim/engine/probes/general_educational/assets/general_educational/en_GB/subjects.json
diff --git a/src/usersim/engine/assets/general_educational/subjects/base/subjects.json b/src/usersim/engine/probes/general_educational/assets/general_educational/en_US/subjects.json
similarity index 100%
rename from src/usersim/engine/assets/general_educational/subjects/base/subjects.json
rename to src/usersim/engine/probes/general_educational/assets/general_educational/en_US/subjects.json
diff --git a/src/usersim/engine/assets/general_educational/subjects/fr_FR/subjects.json b/src/usersim/engine/probes/general_educational/assets/general_educational/fr_FR/subjects.json
similarity index 100%
rename from src/usersim/engine/assets/general_educational/subjects/fr_FR/subjects.json
rename to src/usersim/engine/probes/general_educational/assets/general_educational/fr_FR/subjects.json
diff --git a/src/usersim/engine/assets/general_educational/subjects/hi_Deva_IN/subjects.json b/src/usersim/engine/probes/general_educational/assets/general_educational/hi_Deva_IN/subjects.json
similarity index 100%
rename from src/usersim/engine/assets/general_educational/subjects/hi_Deva_IN/subjects.json
rename to src/usersim/engine/probes/general_educational/assets/general_educational/hi_Deva_IN/subjects.json
diff --git a/src/usersim/engine/assets/general_educational/subjects/hi_Latn_IN/subjects.json b/src/usersim/engine/probes/general_educational/assets/general_educational/hi_Latn_IN/subjects.json
similarity index 100%
rename from src/usersim/engine/assets/general_educational/subjects/hi_Latn_IN/subjects.json
rename to src/usersim/engine/probes/general_educational/assets/general_educational/hi_Latn_IN/subjects.json
diff --git a/src/usersim/engine/assets/general_educational/subjects/ja_JP/subjects.json b/src/usersim/engine/probes/general_educational/assets/general_educational/ja_JP/subjects.json
similarity index 100%
rename from src/usersim/engine/assets/general_educational/subjects/ja_JP/subjects.json
rename to src/usersim/engine/probes/general_educational/assets/general_educational/ja_JP/subjects.json
diff --git a/src/usersim/engine/assets/general_educational/subjects/ko_KR/subjects.json b/src/usersim/engine/probes/general_educational/assets/general_educational/ko_KR/subjects.json
similarity index 100%
rename from src/usersim/engine/assets/general_educational/subjects/ko_KR/subjects.json
rename to src/usersim/engine/probes/general_educational/assets/general_educational/ko_KR/subjects.json
diff --git a/src/usersim/engine/assets/general_educational/prompts.yaml b/src/usersim/engine/probes/general_educational/assets/general_educational/prompts.yaml
similarity index 100%
rename from src/usersim/engine/assets/general_educational/prompts.yaml
rename to src/usersim/engine/probes/general_educational/assets/general_educational/prompts.yaml
diff --git a/src/usersim/engine/assets/general_educational/subjects/pt_BR/subjects.json b/src/usersim/engine/probes/general_educational/assets/general_educational/pt_BR/subjects.json
similarity index 100%
rename from src/usersim/engine/assets/general_educational/subjects/pt_BR/subjects.json
rename to src/usersim/engine/probes/general_educational/assets/general_educational/pt_BR/subjects.json
diff --git a/src/usersim/engine/probes/general_educational/generator.py b/src/usersim/engine/probes/general_educational/probe.py
similarity index 95%
rename from src/usersim/engine/probes/general_educational/generator.py
rename to src/usersim/engine/probes/general_educational/probe.py
index 676f701c..6031c5f2 100644
--- a/src/usersim/engine/probes/general_educational/generator.py
+++ b/src/usersim/engine/probes/general_educational/probe.py
@@ -11,6 +11,7 @@
 
 from __future__ import annotations
 
+from pathlib import Path
 from typing import Any
 
 from usersim.engine.core.behavioral import (
@@ -52,6 +53,7 @@ class EducationalProbe(BaseProbe):
     """
 
     label = "general_educational"
+    assets_root = Path(__file__).parent / "assets"
     description = (
         "Tests tutoring: a persona-grounded learner asks about a subject, and the probe "
         "looks at whether explanations are accurate, pitched at the learner's level and "
@@ -61,7 +63,7 @@ class EducationalProbe(BaseProbe):
 
     @classmethod
     def themes(cls, locale: str) -> list[dict[str, Any]]:
-        """The subjects in ``locale``'s seed file, or in the base file when the locale has none."""
+        """The subjects in ``locale``'s seed file, or in the ``en_US`` file when the locale has none."""
         return load_seeds(locale, cls.label, "subjects")
 
     @classmethod
@@ -133,7 +135,7 @@ async def simulate_general_educational(
 ) -> dict:
     """Thin shim for callers that import ``simulate_general_educational`` directly.
 
-    See ``usersim.engine.probes.general_open_ended.generator.simulate_general_open_ended``
+    See ``usersim.engine.probes.general_open_ended.probe.simulate_general_open_ended``
     for the rationale; preserved for backward-compat with the dispatcher
     bootstrap and per-probe tests.
     """
diff --git a/src/usersim/engine/assets/general_open_ended/topics/de_DE/topics.json b/src/usersim/engine/probes/general_open_ended/assets/general_open_ended/de_DE/topics.json
similarity index 100%
rename from src/usersim/engine/assets/general_open_ended/topics/de_DE/topics.json
rename to src/usersim/engine/probes/general_open_ended/assets/general_open_ended/de_DE/topics.json
diff --git a/src/usersim/engine/assets/general_open_ended/topics/en_GB/topics.json b/src/usersim/engine/probes/general_open_ended/assets/general_open_ended/en_GB/topics.json
similarity index 100%
rename from src/usersim/engine/assets/general_open_ended/topics/en_GB/topics.json
rename to src/usersim/engine/probes/general_open_ended/assets/general_open_ended/en_GB/topics.json
diff --git a/src/usersim/engine/assets/general_open_ended/topics/base/topics.json b/src/usersim/engine/probes/general_open_ended/assets/general_open_ended/en_US/topics.json
similarity index 100%
rename from src/usersim/engine/assets/general_open_ended/topics/base/topics.json
rename to src/usersim/engine/probes/general_open_ended/assets/general_open_ended/en_US/topics.json
diff --git a/src/usersim/engine/assets/general_open_ended/topics/fr_FR/topics.json b/src/usersim/engine/probes/general_open_ended/assets/general_open_ended/fr_FR/topics.json
similarity index 100%
rename from src/usersim/engine/assets/general_open_ended/topics/fr_FR/topics.json
rename to src/usersim/engine/probes/general_open_ended/assets/general_open_ended/fr_FR/topics.json
diff --git a/src/usersim/engine/assets/general_open_ended/topics/hi_Deva_IN/topics.json b/src/usersim/engine/probes/general_open_ended/assets/general_open_ended/hi_Deva_IN/topics.json
similarity index 100%
rename from src/usersim/engine/assets/general_open_ended/topics/hi_Deva_IN/topics.json
rename to src/usersim/engine/probes/general_open_ended/assets/general_open_ended/hi_Deva_IN/topics.json
diff --git a/src/usersim/engine/assets/general_open_ended/topics/hi_Latn_IN/topics.json b/src/usersim/engine/probes/general_open_ended/assets/general_open_ended/hi_Latn_IN/topics.json
similarity index 100%
rename from src/usersim/engine/assets/general_open_ended/topics/hi_Latn_IN/topics.json
rename to src/usersim/engine/probes/general_open_ended/assets/general_open_ended/hi_Latn_IN/topics.json
diff --git a/src/usersim/engine/assets/general_open_ended/topics/ja_JP/topics.json b/src/usersim/engine/probes/general_open_ended/assets/general_open_ended/ja_JP/topics.json
similarity index 100%
rename from src/usersim/engine/assets/general_open_ended/topics/ja_JP/topics.json
rename to src/usersim/engine/probes/general_open_ended/assets/general_open_ended/ja_JP/topics.json
diff --git a/src/usersim/engine/assets/general_open_ended/topics/ko_KR/topics.json b/src/usersim/engine/probes/general_open_ended/assets/general_open_ended/ko_KR/topics.json
similarity index 100%
rename from src/usersim/engine/assets/general_open_ended/topics/ko_KR/topics.json
rename to src/usersim/engine/probes/general_open_ended/assets/general_open_ended/ko_KR/topics.json
diff --git a/src/usersim/engine/assets/general_open_ended/prompts.yaml b/src/usersim/engine/probes/general_open_ended/assets/general_open_ended/prompts.yaml
similarity index 100%
rename from src/usersim/engine/assets/general_open_ended/prompts.yaml
rename to src/usersim/engine/probes/general_open_ended/assets/general_open_ended/prompts.yaml
diff --git a/src/usersim/engine/assets/general_open_ended/topics/pt_BR/topics.json b/src/usersim/engine/probes/general_open_ended/assets/general_open_ended/pt_BR/topics.json
similarity index 100%
rename from src/usersim/engine/assets/general_open_ended/topics/pt_BR/topics.json
rename to src/usersim/engine/probes/general_open_ended/assets/general_open_ended/pt_BR/topics.json
diff --git a/src/usersim/engine/probes/general_open_ended/generator.py b/src/usersim/engine/probes/general_open_ended/probe.py
similarity index 97%
rename from src/usersim/engine/probes/general_open_ended/generator.py
rename to src/usersim/engine/probes/general_open_ended/probe.py
index e9aeacc0..767ac12e 100644
--- a/src/usersim/engine/probes/general_open_ended/generator.py
+++ b/src/usersim/engine/probes/general_open_ended/probe.py
@@ -11,6 +11,7 @@
 
 from __future__ import annotations
 
+from pathlib import Path
 from typing import Any
 
 from usersim.engine.core.behavioral import (
@@ -51,6 +52,7 @@ class OpenEndedProbe(BaseProbe):
     """
 
     label = "general_open_ended"
+    assets_root = Path(__file__).parent / "assets"
     description = (
         "Tests information-seeking conversations across diverse personas: accurate, "
         "coherent answers pitched to the user's apparent expertise, and a clarifying "
@@ -60,7 +62,7 @@ class OpenEndedProbe(BaseProbe):
 
     @classmethod
     def themes(cls, locale: str) -> list[dict[str, Any]]:
-        """The topics in ``locale``'s seed file, or in the base file when the locale has none."""
+        """The topics in ``locale``'s seed file, or in the ``en_US`` file when the locale has none."""
         return load_seeds(locale, cls.label, "topics")
 
     @classmethod
diff --git a/src/usersim/engine/probes/tool_calling/generator.py b/src/usersim/engine/probes/tool_calling/generator.py
index 7258e6a0..8bc47abe 100644
--- a/src/usersim/engine/probes/tool_calling/generator.py
+++ b/src/usersim/engine/probes/tool_calling/generator.py
@@ -72,7 +72,7 @@
 logger = logging.getLogger("usersim.engine")
 
 # ── Scenario metadata ────────────────────────────────────────────────
-# See general_educational/generator.py for the contract. `probe_variant` is
+# See general_educational/probe.py for the contract. `probe_variant` is
 # carried on the trajectory; the evaluator reads it for stratification.
 
 PROBE_FAMILY: str = "tool_calling"
diff --git a/templates/probe/README.md b/templates/probe/README.md
index f004d6f9..942e7e9b 100644
--- a/templates/probe/README.md
+++ b/templates/probe/README.md
@@ -44,8 +44,9 @@ templates/probe/
 
 When you port the template, copy the `generator_<shape>.py` whose
 shape matches your probe into
-`src/usersim/engine/probes/<your_probe>/generator.py`,
-copy `prompts.py` into the same directory, and copy
+`src/usersim/engine/probes/<your_probe>/probe.py`,
+copy `prompts.py` into the same directory, put its banks in that
+directory's `assets/<your_probe>/`, and copy
 `test_probe.py.template` to
 `tests/engine/probes/test_<your_probe>.py`. Then follow the
 authoring tutorial.
@@ -56,9 +57,10 @@ A probe class is a `BaseProbe` subclass (plus an optional mixin)
 decorated with `@register_probe(...)`. The decorator sets three
 class attributes (`family` / `prompt_version` / `variants`); the
 smoke check verifies they're present. A probe ported from this template
-keeps its banks under `src/usersim/engine/assets/<your_probe>/` and leaves
-`assets_root` unset; a probe shipped in its own package sets it, and its
-bank loader reads under `assets_dir()`, as
+keeps its banks beside its code, under
+`src/usersim/engine/probes/<your_probe>/assets/<your_probe>/`, and sets
+`assets_root` to that `assets/` folder, as a probe shipped in its own
+package does. Its bank loader reads under `assets_dir()`, as
 `docs/engine/AUTHORING_A_PROBE.md` step 2 shows.
 
 The runtime `ProbeAdapter` contract has 8 required hooks: class-level
diff --git a/templates/probe/generator_agentic.py b/templates/probe/generator_agentic.py
index 5eef7edc..4cf22af6 100644
--- a/templates/probe/generator_agentic.py
+++ b/templates/probe/generator_agentic.py
@@ -47,6 +47,7 @@
 from __future__ import annotations
 
 from dataclasses import dataclass
+from pathlib import Path
 from typing import Any
 
 from usersim.extension import (
@@ -84,6 +85,7 @@ class DemoAgenticProbe(AgenticMixin, BankBackedProbe):
     """Single-user-turn + multi-assistant-turn tool-interception probe."""
 
     label = "demo_agentic"
+    assets_root = Path(__file__).parent / "assets"  # holds demo_agentic/, beside this module
     output_columns = ("action_request_id", "sub_protocol")
     bank_loader = staticmethod(_demo_agentic_loader)
     placeholder_warning_kind = WarningKind.USED_PLACEHOLDER_AGENTIC_ACTION
diff --git a/templates/probe/generator_bank_reframing.py b/templates/probe/generator_bank_reframing.py
index 0fda1ff4..b5447fff 100644
--- a/templates/probe/generator_bank_reframing.py
+++ b/templates/probe/generator_bank_reframing.py
@@ -59,6 +59,7 @@
 from __future__ import annotations
 
 from dataclasses import dataclass
+from pathlib import Path
 from typing import Any
 
 from usersim.extension import (
@@ -116,6 +117,7 @@ class DemoBankReframingProbe(BankReframingMixin, BankBackedProbe):
     """Multi-turn reframing-rotation probe."""
 
     label = "demo_bank_reframing"
+    assets_root = Path(__file__).parent / "assets"  # holds demo_bank_reframing/, beside this module
     output_columns = ("target_request_id", "strategy_id", "reframings_used")
     bank_loader = staticmethod(_demo_pressure_loader)
     placeholder_warning_kind = WarningKind.USED_PLACEHOLDER_TARGET
diff --git a/templates/probe/generator_bank_verbatim.py b/templates/probe/generator_bank_verbatim.py
index cd13026c..29d4013f 100644
--- a/templates/probe/generator_bank_verbatim.py
+++ b/templates/probe/generator_bank_verbatim.py
@@ -103,6 +103,7 @@ class DemoBankVerbatimProbe(BankVerbatimMixin, BankBackedProbe):
     """
 
     label = "demo_bank_verbatim"
+    assets_root = Path(__file__).parent / "assets"  # holds demo_bank_verbatim/, beside this module
     output_columns = ("sovereign_facts_probed",)
     bank_loader = staticmethod(_demo_bank_loader)
     placeholder_warning_kind = WarningKind.USED_PLACEHOLDER_FACT
diff --git a/templates/probe/generator_custom_turn1.py b/templates/probe/generator_custom_turn1.py
index c80f5084..0a5f3737 100644
--- a/templates/probe/generator_custom_turn1.py
+++ b/templates/probe/generator_custom_turn1.py
@@ -42,6 +42,7 @@
 from __future__ import annotations
 
 from dataclasses import dataclass
+from pathlib import Path
 from typing import Any
 
 from usersim.extension import BankBackedProbe, WarningKind, register_probe
@@ -68,6 +69,7 @@ class DemoCustomTurn1Probe(BankBackedProbe):
     """Bank-anchored, generated-in-voice turn-1 probe."""
 
     label = "demo_custom_turn1"
+    assets_root = Path(__file__).parent / "assets"  # holds demo_custom_turn1/, beside this module
     output_columns = ("probing_categories_explored", "probing_subtopic_hints_used")
     bank_loader = staticmethod(_demo_taxonomy_loader)
     placeholder_warning_kind = WarningKind.USED_PLACEHOLDER_TAXONOMY
diff --git a/templates/probe/test_probe.py.template b/templates/probe/test_probe.py.template
index c9b64423..c22c5b79 100644
--- a/templates/probe/test_probe.py.template
+++ b/templates/probe/test_probe.py.template
@@ -65,7 +65,7 @@ from usersim.testing import assert_probe_conforms, run_episode
 
 # Replace with your probe's module + names.
 from usersim.engine.probes.YOUR_PROBE import (
-    generator as probe_gen,
+    probe as probe_gen,
 )
 
 PROBE_LABEL = "YOUR_PROBE"
diff --git a/tests/engine/core/test_assets_discovery.py b/tests/engine/core/test_assets_discovery.py
index 14e04200..67d6a818 100644
--- a/tests/engine/core/test_assets_discovery.py
+++ b/tests/engine/core/test_assets_discovery.py
@@ -19,8 +19,10 @@
 from __future__ import annotations
 
 import os
+import sys
 from pathlib import Path
 
+import usersim
 from usersim.engine.core._assets import (
     asset_roots_in_use,
     asset_search_path,
@@ -98,8 +100,24 @@ def test_every_registered_probe_resolves_to_a_folder(self) -> None:
         assert not unresolved, f"registered probes without an asset folder: {unresolved}"
 
     def test_every_built_in_probe_ships_its_folder_in_the_package(self) -> None:
-        missing = sorted(label for label in self._labels() if not (packaged_assets_dir() / label).is_dir())
-        assert not missing, f"built-in probes whose assets are not under {packaged_assets_dir()}: {missing}"
+        """In the packaged banks or in the probe's own folder, so a plain install has it."""
+        package = Path(usersim.__file__).parent
+        outside = {
+            label: probe_assets_dir(label)
+            for label in self._labels()
+            if not probe_assets_dir(label).is_relative_to(package)
+        }
+        assert not outside, f"built-in probes whose assets are outside {package}: {outside}"
+
+    def test_a_built_in_that_declares_a_root_keeps_it_in_its_own_folder(self) -> None:
+        """Its banks sit beside its code, at ``engine/probes/<label>/assets/<label>/``."""
+        from usersim.engine.core.probes import resolve_probe
+
+        declared = {label: resolve_probe(label) for label in self._labels() if resolve_probe(label).assets_root}
+        assert declared, "no built-in probe declares an assets_root"
+        for label, cls in declared.items():
+            folder = Path(sys.modules[cls.__module__].__file__).parent
+            assert folder.name == label and Path(cls.assets_root) == folder / "assets", label
 
     def test_packaged_tree_has_no_stray_top_level_entries(self) -> None:
         """Everything shipped under assets/ should be a probe folder. Catches
@@ -241,11 +259,11 @@ def test_a_declared_root_serves_only_its_own_probe(self, register_test_probe, tm
         assert probe_assets_dir("tool_calling") == packaged_assets_dir() / "tool_calling"
 
     def test_roots_in_use_add_declared_roots_after_the_search_path(self, register_test_probe, tmp_path) -> None:
-        assert asset_roots_in_use() == asset_search_path()
-
         register_test_probe("ext_probe", assets_root=tmp_path)
 
-        assert asset_roots_in_use() == (*asset_search_path(), tmp_path)
+        roots, search = asset_roots_in_use(), asset_search_path()
+        assert roots[: len(search)] == search
+        assert tmp_path in roots[len(search) :]
 
 
 class TestProbeAssetsDir:
@@ -270,3 +288,43 @@ def test_a_deliberate_override_reaches_the_probe(self, register_test_probe, monk
         probe = register_test_probe("ext_probe", assets_root=declared)
 
         assert probe.assets_dir() == override / "ext_probe"
+
+
+class TestPinnedPackagedRoot:
+    """Pinning the packaged directory pins the assets that ship with User Sim."""
+
+    @staticmethod
+    def _package(monkeypatch, tmp_path: Path) -> Path:
+        """A stand-in ``usersim`` package whose packaged banks are at ``engine/assets/``."""
+        import usersim.engine.core._assets as assets
+
+        package = tmp_path / "usersim"
+        (package / "engine" / "assets").mkdir(parents=True)
+        monkeypatch.setattr(assets, "packaged_assets_dir", lambda: package / "engine" / "assets")
+        return package
+
+    def test_it_reaches_a_probe_whose_banks_are_in_its_own_folder_in_the_package(
+        self, register_test_probe, monkeypatch, tmp_path
+    ) -> None:
+        package = self._package(monkeypatch, tmp_path)
+        own = package / "engine" / "probes" / "ext_probe" / "assets"
+        (own / "ext_probe").mkdir(parents=True)
+        register_test_probe("ext_probe", assets_root=own)
+
+        assert probe_assets_dir("ext_probe", assets_root=package / "engine" / "assets") == own / "ext_probe"
+
+    def test_it_stays_strict_for_a_root_outside_the_package(self, register_test_probe, monkeypatch, tmp_path) -> None:
+        package = self._package(monkeypatch, tmp_path)
+        (tmp_path / "extension" / "ext_probe").mkdir(parents=True)
+        register_test_probe("ext_probe", assets_root=tmp_path / "extension")
+
+        pinned = package / "engine" / "assets"
+        assert probe_assets_dir("ext_probe", assets_root=pinned) == pinned / "ext_probe"
+
+    def test_any_other_pinned_root_stays_strict(self, register_test_probe, monkeypatch, tmp_path) -> None:
+        package = self._package(monkeypatch, tmp_path)
+        own = package / "engine" / "probes" / "ext_probe" / "assets"
+        (own / "ext_probe").mkdir(parents=True)
+        register_test_probe("ext_probe", assets_root=own)
+
+        assert probe_assets_dir("ext_probe", assets_root=tmp_path / "mine") == tmp_path / "mine" / "ext_probe"
diff --git a/tests/engine/core/test_default_asset_paths.py b/tests/engine/core/test_default_asset_paths.py
index 19dd09b1..5add8721 100644
--- a/tests/engine/core/test_default_asset_paths.py
+++ b/tests/engine/core/test_default_asset_paths.py
@@ -158,7 +158,7 @@ def test_seeds_default_path_loads_for_every_locale(
     kind: str,
 ) -> None:
     """``load_seeds`` raises ``FileNotFoundError`` when neither the
-    locale-specific file nor the ``base/`` fallback exists. We assert
+    locale's own file nor the ``en_US`` fallback exists. We assert
     a non-empty result so a bug that ships an empty file (or points at
     one) also fails."""
     seeds = load_seeds(locale, probe, kind)
diff --git a/tests/engine/core/test_multi_locale.py b/tests/engine/core/test_multi_locale.py
index 43def147..f82ce2ba 100644
--- a/tests/engine/core/test_multi_locale.py
+++ b/tests/engine/core/test_multi_locale.py
@@ -6,13 +6,12 @@
 import pytest
 
 from usersim.engine.config import ConversationSimulatorConfig
-from usersim.engine.core._assets import packaged_assets_dir
+from usersim.engine.core._assets import probe_assets_dir
 from usersim.engine.core.behavioral import LOCALE_LANGUAGE_MAP, get_conversation_language
 from usersim.engine.core.locale import SHIPPED_LOCALES
-from usersim.engine.core.seeds import load_seeds
+from usersim.engine.core.seeds import FALLBACK_LOCALE, load_seeds
 
 LOCALES = SHIPPED_LOCALES
-ASSETS_DIR = packaged_assets_dir()
 
 
 class TestMultiLocaleLoop:
@@ -46,28 +45,29 @@ class TestLocaleSeeds:
 
     @pytest.fixture(autouse=True)
     def check_assets(self):
-        # Fail rather than skip: the seeds are package data, so their absence
-        # is a packaging defect, not an environment the test can excuse.
-        base = ASSETS_DIR / "general_open_ended" / "topics" / "base"
-        assert base.is_dir(), f"packaged seeds missing at {base}"
+        # Fail rather than skip: the seeds ship with the package, so their
+        # absence is a packaging defect, not an environment the test can excuse.
+        for probe, kind in [("general_open_ended", "topics"), ("general_educational", "subjects")]:
+            fallback = probe_assets_dir(probe) / FALLBACK_LOCALE / f"{kind}.json"
+            assert fallback.is_file(), f"packaged seeds missing at {fallback}"
 
-    def test_base_seeds_available_for_all_locales(self):
+    def test_seeds_available_for_all_locales(self):
         for locale in LOCALES:
-            topics = load_seeds(locale, "general_open_ended", "topics", ASSETS_DIR)
-            assert len(topics) >= 15  # base has 15
+            topics = load_seeds(locale, "general_open_ended", "topics")
+            assert len(topics) >= 15  # ja_JP and ko_KR, the smallest, have 15
 
-            subjects = load_seeds(locale, "general_educational", "subjects", ASSETS_DIR)
-            assert len(subjects) >= 10  # base has 10
+            subjects = load_seeds(locale, "general_educational", "subjects")
+            assert len(subjects) >= 10  # pt_BR, the smallest, has 10
 
     def test_locale_seed_counts_preserve_localized_replacements(self):
-        base_count = len(load_seeds("en_US", "general_open_ended", "topics", ASSETS_DIR))
-        pt_count = len(load_seeds("pt_BR", "general_open_ended", "topics", ASSETS_DIR))
-        assert base_count == 48
+        us_count = len(load_seeds("en_US", "general_open_ended", "topics"))
+        pt_count = len(load_seeds("pt_BR", "general_open_ended", "topics"))
+        assert us_count == 48
         assert pt_count == 20
 
-        base_ed = len(load_seeds("en_US", "general_educational", "subjects", ASSETS_DIR))
-        ja_ed = len(load_seeds("ja_JP", "general_educational", "subjects", ASSETS_DIR))
-        assert base_ed == 40
+        us_ed = len(load_seeds("en_US", "general_educational", "subjects"))
+        ja_ed = len(load_seeds("ja_JP", "general_educational", "subjects"))
+        assert us_ed == 40
         assert ja_ed == 14
 
     def test_seed_kinds_have_required_fields(self):
@@ -76,7 +76,7 @@ def test_seed_kinds_have_required_fields(self):
                 ("general_open_ended", "topics"),
                 ("general_educational", "subjects"),
             ]:
-                seeds = load_seeds(locale, probe, kind, ASSETS_DIR)
+                seeds = load_seeds(locale, probe, kind)
                 for seed in seeds:
                     assert "type" in seed, f"Missing 'type' in {probe}/{kind} for {locale}"
                     assert "description" in seed, f"Missing 'description' in {probe}/{kind} for {locale}"
diff --git a/tests/engine/core/test_pipeline.py b/tests/engine/core/test_pipeline.py
index 75d9fb6f..fa9b6fc0 100644
--- a/tests/engine/core/test_pipeline.py
+++ b/tests/engine/core/test_pipeline.py
@@ -8,10 +8,7 @@
 and are marked with @pytest.mark.integration.
 """
 
-import pytest
-
 from usersim.engine.config import ConversationSimulatorConfig
-from usersim.engine.core._assets import packaged_assets_dir
 from usersim.engine.core.behavioral import compute_behavioral_profile, get_conversation_language
 from usersim.engine.core.locale import SHIPPED_LOCALES
 from usersim.engine.core.seeds import load_seeds
@@ -111,23 +108,15 @@ class TestMultiLocaleConsistency:
     """Verify multi-locale support is consistent."""
 
     def test_seed_loading_per_locale(self):
-        assets = packaged_assets_dir()
-        if not (assets / "general_open_ended" / "topics" / "base").exists():
-            pytest.skip("Assets directory not found")
-
         for locale in SHIPPED_LOCALES:
-            topics = load_seeds(locale, "general_open_ended", "topics", assets)
+            topics = load_seeds(locale, "general_open_ended", "topics")
             assert len(topics) > 0
             assert all(isinstance(t, dict) for t in topics)
             assert all("type" in t and "description" in t for t in topics)
 
     def test_pt_br_keeps_localized_topic_replacement(self):
-        assets = packaged_assets_dir()
-        if not (assets / "general_open_ended" / "topics" / "base").exists():
-            pytest.skip("Assets directory not found")
-
-        base = load_seeds("en_US", "general_open_ended", "topics", assets)
-        extended = load_seeds("pt_BR", "general_open_ended", "topics", assets)
+        base = load_seeds("en_US", "general_open_ended", "topics")
+        extended = load_seeds("pt_BR", "general_open_ended", "topics")
         assert len(base) == 48
         assert len(extended) == 20
 
diff --git a/tests/engine/core/test_prompt_resolution.py b/tests/engine/core/test_prompt_resolution.py
index 68c52ad8..4c4402b7 100644
--- a/tests/engine/core/test_prompt_resolution.py
+++ b/tests/engine/core/test_prompt_resolution.py
@@ -25,8 +25,8 @@
 import pytest
 import yaml
 
-from usersim.engine.core._assets import packaged_assets_dir, set_runtime_assets_dir
-from usersim.engine.core.prompt_loader import render_prompt
+from usersim.engine.core._assets import probe_assets_dir, set_runtime_assets_dir
+from usersim.engine.core.prompt_loader import get_prompt, load_prompt_file, render_prompt
 
 #: The theme-driven probes, mapped to the name each one gives the
 #: import-time constant behind ``user_agent_system_prompt()``. Spelled out
@@ -155,6 +155,24 @@ def test_missing_key_falls_back_to_the_compiled_default(self, tmp_path):
         assert oe.trajectory_rubric() == "R"
 
 
+class TestPromptFileIsReadWhereTheBanksAre:
+    """A probe's ``prompts.yaml`` comes from the folder its banks resolve to."""
+
+    def test_a_root_holding_other_probes_does_not_hide_the_shipped_prompts(self, tmp_path):
+        set_runtime_assets_dir(_assets_with_prompt(tmp_path, "tool_calling", user_agent_system_prompt="OTHER"))
+
+        shipped = yaml.safe_load((probe_assets_dir("general_open_ended") / "prompts.yaml").read_text())
+        assert shipped
+        assert load_prompt_file("general_open_ended") == shipped
+
+    def test_a_declared_root_supplies_its_probes_prompts(self, register_test_probe, tmp_path):
+        register_test_probe(
+            "ext_probe", assets_root=_assets_with_prompt(tmp_path, "ext_probe", user_agent_system_prompt="EXT")
+        )
+
+        assert get_prompt("ext_probe", "user_agent_system_prompt") == "EXT"
+
+
 # ---------------------------------------------------------------------------
 # Per-row wiring
 # ---------------------------------------------------------------------------
@@ -180,7 +198,7 @@ class _Cfg:
 def _open_ended_probe(data: dict):
     """A real ``OpenEndedProbe`` for ``data``, with no LLM anywhere near it."""
     from usersim.engine.core.behavioral import compute_behavioral_profile
-    from usersim.engine.probes.general_open_ended.generator import OpenEndedProbe
+    from usersim.engine.probes.general_open_ended.probe import OpenEndedProbe
 
     persona = {"first_name": "A", "last_name": "B", "age": 30, "sex": "female"}
     return OpenEndedProbe(
@@ -263,7 +281,7 @@ def test_each_row_renders_its_own_values(self, tmp_path):
         """The dispatcher constructs a probe per row, so a row column
         referenced from prompts.yaml must reflect THAT row."""
         from usersim.engine.core.behavioral import compute_behavioral_profile
-        from usersim.engine.probes.general_open_ended.generator import (
+        from usersim.engine.probes.general_open_ended.probe import (
             OpenEndedProbe,
         )
 
@@ -363,7 +381,7 @@ def test_override_is_scoped_to_one_probe(self, tmp_path):
         every other probe on the default."""
         from usersim.engine.core.behavioral import compute_behavioral_profile
         from usersim.engine.core.prompts import ASSISTANT_JUDGE_PROMPT
-        from usersim.engine.probes.general_educational.generator import (
+        from usersim.engine.probes.general_educational.probe import (
             EducationalProbe,
         )
 
@@ -426,5 +444,5 @@ def test_shipped_asset_matches_the_compiled_default(self, probe):
 
         from usersim.engine.core.prompts import ASSISTANT_JUDGE_PROMPT
 
-        shipped = yaml.safe_load((packaged_assets_dir() / probe / "prompts.yaml").read_text())
+        shipped = yaml.safe_load((probe_assets_dir(probe) / "prompts.yaml").read_text())
         assert shipped["assistant_judge_prompt"] == ASSISTANT_JUDGE_PROMPT
diff --git a/tests/engine/core/test_provenance.py b/tests/engine/core/test_provenance.py
index 4b92dbaa..d320a452 100644
--- a/tests/engine/core/test_provenance.py
+++ b/tests/engine/core/test_provenance.py
@@ -162,8 +162,8 @@ def test_env_override(self, monkeypatch: pytest.MonkeyPatch) -> None:
 @pytest.mark.parametrize(
     "module_path",
     [
-        "usersim.engine.probes.general_open_ended.generator",
-        "usersim.engine.probes.general_educational.generator",
+        "usersim.engine.probes.general_open_ended.probe",
+        "usersim.engine.probes.general_educational.probe",
         "usersim.engine.probes.tool_calling.generator",
     ],
 )
diff --git a/tests/engine/core/test_reasoning_replay.py b/tests/engine/core/test_reasoning_replay.py
index c60469b3..9f9639e2 100644
--- a/tests/engine/core/test_reasoning_replay.py
+++ b/tests/engine/core/test_reasoning_replay.py
@@ -158,7 +158,7 @@ async def test_a_hosted_episode_replays_as_a_local_one_does(probe_type):
 async def test_a_probe_shortcut_replays_as_the_generator_does():
     """The public ``simulate_<probe>`` functions promise the dispatcher path's behaviour."""
     from usersim.engine.core.episode_input import construct_episode_preamble
-    from usersim.engine.probes.general_open_ended.generator import simulate_general_open_ended
+    from usersim.engine.probes.general_open_ended.probe import simulate_general_open_ended
 
     cfg = _config("general_open_ended", replay_assistant_reasoning=True)
     prompts: list[dict[str, Any]] = []
diff --git a/tests/engine/core/test_seeds.py b/tests/engine/core/test_seeds.py
index e0df6092..c9af6c97 100644
--- a/tests/engine/core/test_seeds.py
+++ b/tests/engine/core/test_seeds.py
@@ -1,7 +1,7 @@
 # SPDX-FileCopyrightText: Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
 # SPDX-License-Identifier: Apache-2.0
 
-"""Tests for core/seeds.py — per-probe seed loader with locale fallback."""
+"""Tests for core/seeds.py: the per-probe seed loader and its en_US fallback."""
 
 import json
 from pathlib import Path
@@ -16,36 +16,36 @@ def seed_dir(tmp_path):
     """Build the per-probe layout this loader expects:
 
     tmp_path/
-      general_open_ended/topics/{base,pt_BR}/topics.json
-      general_educational/subjects/base/subjects.json
+      general_open_ended/{en_US,pt_BR}/topics.json
+      general_educational/en_US/subjects.json
     """
-    oe_base = tmp_path / "general_open_ended" / "topics" / "base"
-    oe_base.mkdir(parents=True)
-    base_topics = [
+    oe_us = tmp_path / "general_open_ended" / "en_US"
+    oe_us.mkdir(parents=True)
+    us_topics = [
         {"type": "health", "description": "Health topics"},
         {"type": "finance", "description": "Finance topics"},
     ]
-    (oe_base / "topics.json").write_text(json.dumps(base_topics))
+    (oe_us / "topics.json").write_text(json.dumps(us_topics))
 
-    oe_pt = tmp_path / "general_open_ended" / "topics" / "pt_BR"
+    oe_pt = tmp_path / "general_open_ended" / "pt_BR"
     oe_pt.mkdir(parents=True)
     pt_topics = [{"type": "sus", "description": "SUS healthcare"}]
     (oe_pt / "topics.json").write_text(json.dumps(pt_topics))
 
-    ed_base = tmp_path / "general_educational" / "subjects" / "base"
-    ed_base.mkdir(parents=True)
-    (ed_base / "subjects.json").write_text(json.dumps([{"type": "math", "description": "Mathematics"}]))
+    ed_us = tmp_path / "general_educational" / "en_US"
+    ed_us.mkdir(parents=True)
+    (ed_us / "subjects.json").write_text(json.dumps([{"type": "math", "description": "Mathematics"}]))
 
     return tmp_path
 
 
 class TestLoadSeeds:
-    def test_loads_base_only(self, seed_dir: Path) -> None:
+    def test_en_us_reads_its_own_file(self, seed_dir: Path) -> None:
         seeds = load_seeds("en_US", "general_open_ended", "topics", seed_dir)
         assert len(seeds) == 2
         assert seeds[0]["type"] == "health"
 
-    def test_locale_replaces_base(self, seed_dir: Path) -> None:
+    def test_a_locale_file_replaces_the_en_us_one(self, seed_dir: Path) -> None:
         seeds = load_seeds("pt_BR", "general_open_ended", "topics", seed_dir)
         assert len(seeds) == 1
         assert seeds[0]["type"] == "sus"
@@ -58,9 +58,9 @@ def test_missing_probe_raises(self, seed_dir: Path) -> None:
         with pytest.raises(FileNotFoundError):
             load_seeds("en_US", "no_such_probe", "topics", seed_dir)
 
-    def test_locale_without_translation_falls_back_to_base(self, seed_dir: Path) -> None:
+    def test_a_locale_without_a_file_reads_the_en_us_one(self, seed_dir: Path) -> None:
         seeds = load_seeds("ja_JP", "general_open_ended", "topics", seed_dir)
-        assert len(seeds) == 2
+        assert [s["type"] for s in seeds] == ["health", "finance"]
 
     def test_educational_kind_loads(self, seed_dir: Path) -> None:
         seeds = load_seeds("en_US", "general_educational", "subjects", seed_dir)
diff --git a/tests/engine/test_undeclared_result_columns.py b/tests/engine/test_undeclared_result_columns.py
index c3f715a5..7c45596a 100644
--- a/tests/engine/test_undeclared_result_columns.py
+++ b/tests/engine/test_undeclared_result_columns.py
@@ -27,7 +27,7 @@
 from usersim.engine.core.episode_input import ConstructedEpisode
 from usersim.engine.core.probes import _PROBE_REGISTRY, clear_registry, load_builtin_probes, register_probe
 from usersim.engine.generator import ConversationSimulatorGenerator
-from usersim.engine.probes.general_open_ended.generator import OpenEndedProbe
+from usersim.engine.probes.general_open_ended.probe import OpenEndedProbe
 
 _PROBE = "_extra_column_probe"
 _PERSONA = {"first_name": "Sarah", "last_name": "Johnson", "age": 35, "city": "Seattle", "state": "WA"}
diff --git a/tests/test_check_dist.py b/tests/test_check_dist.py
index 95a0fd5f..cb72d69d 100644
--- a/tests/test_check_dist.py
+++ b/tests/test_check_dist.py
@@ -78,8 +78,12 @@ def test_a_package_file_missing_from_the_wheel_is_reported(tmp_path: Path) -> No
     assert len(problems) == 1 and "lacks 1 package file" in problems[0] and spec in problems[0]
 
 
-def test_a_bank_schema_must_ship(tmp_path: Path) -> None:
-    schema = "usersim/engine/assets/probe/SCHEMA.md"
+@pytest.mark.parametrize(
+    "schema",
+    ["usersim/engine/assets/probe/SCHEMA.md", "usersim/engine/probes/probe/assets/probe/SCHEMA.md"],
+    ids=["shared-assets-folder", "probe-folder"],
+)
+def test_a_bank_schema_must_ship(tmp_path: Path, schema: str) -> None:
     problems = check_dist.check_archives(*_pair(tmp_path), package_files=[*_PACKAGE, schema])
     assert len(problems) == 1 and schema in problems[0]
 
diff --git a/tests/test_extension_api.py b/tests/test_extension_api.py
index e965bb99..f4d700a6 100644
--- a/tests/test_extension_api.py
+++ b/tests/test_extension_api.py
@@ -53,7 +53,7 @@
 #: Imports from other ``usersim`` modules that the examples keep, as (module, name).
 _KEPT_INTERNAL_IMPORTS = {
     # A new in-tree probe's own modules, under the names the examples give them.
-    ("usersim.engine.probes.YOUR_PROBE", "generator"),
+    ("usersim.engine.probes.YOUR_PROBE", "probe"),
     ("usersim.engine.probes.bookings.bank", "LOCALES"),
     ("usersim.engine.probes.bookings.bank", "Booking"),
     ("usersim.engine.probes.bookings.bank", "read_booking_bank"),