diff --git a/src/physcom/cli.py b/src/physcom/cli.py
index d7d3a35..83708fb 100644
--- a/src/physcom/cli.py
+++ b/src/physcom/cli.py
@@ -263,5 +263,54 @@ def export(ctx, domain_name, fmt, top, output):
         click.echo(f"Unsupported format: {fmt}")
 
 
+@main.group()
+def snapshot():
+    """Export/import database snapshots."""
+    pass
+
+
+@snapshot.command("export")
+@click.argument("file", type=click.Path())
+@click.option("--pretty/--no-pretty", default=True, help="Pretty-print JSON")
+@click.pass_context
+def snapshot_export(ctx, file, pretty):
+    """Export full database state to a JSON file."""
+    import json
+    from physcom.snapshot import export_snapshot
+
+    repo = _get_repo(ctx.obj["db"])
+    data = export_snapshot(repo)
+    indent = 2 if pretty else None
+    Path(file).write_text(json.dumps(data, indent=indent), encoding="utf-8")
+    click.echo(f"Exported snapshot to {file}")
+    click.echo(f"  {len(data['dimensions'])} dimensions, "
+               f"{len(data['entities'])} entities, "
+               f"{len(data['domains'])} domains, "
+               f"{len(data['combinations'])} combinations, "
+               f"{len(data['results'])} results, "
+               f"{len(data['scores'])} scores")
+
+
+@snapshot.command("load")
+@click.argument("file", type=click.Path(exists=True))
+@click.option("--clear", is_flag=True, help="Wipe database before importing")
+@click.pass_context
+def snapshot_load(ctx, file, clear):
+    """Import a JSON snapshot into the database."""
+    import json
+    from physcom.snapshot import import_snapshot
+
+    repo = _get_repo(ctx.obj["db"])
+    data = json.loads(Path(file).read_text(encoding="utf-8"))
+    counts = import_snapshot(repo, data, clear=clear)
+    click.echo(f"Imported snapshot from {file}" + (" (cleared DB first)" if clear else ""))
+    click.echo(f"  {counts['dimensions']} dimensions, "
+               f"{counts['entities']} entities, "
+               f"{counts['domains']} domains, "
+               f"{counts['combinations']} combinations, "
+               f"{counts['results']} results, "
+               f"{counts['scores']} scores")
+
+
 if __name__ == "__main__":
     main()
diff --git a/src/physcom/engine/constraint_resolver.py b/src/physcom/engine/constraint_resolver.py
index 3b2a120..d6d101c 100644
--- a/src/physcom/engine/constraint_resolver.py
+++ b/src/physcom/engine/constraint_resolver.py
@@ -16,6 +16,23 @@ MUTEX_VALUES: dict[str, list[set[str]]] = {
     "medium": [{"ground"}, {"water"}, {"air"}, {"space"}],
 }
 
+# Conditions assumed always available (don't need an explicit provides)
+AMBIENT_CONDITIONS: set[tuple[str, str]] = {
+    ("ground_surface", "true"),
+    ("gravity", "true"),
+    ("star_proximity", "true"),
+}
+
+# Per-category behavior for unmet requirements:
+#   "block" = hard violation, "warn" = conditional warning, "skip" = ignore
+CATEGORY_SEVERITY: dict[str, str] = {
+    "energy": "block",
+    "infrastructure": "skip",
+}
+
+# For provides-vs-range_min: deficit > this ratio = hard block, else warning
+DEFICIT_THRESHOLD: float = 0.25
+
 
 @dataclass
 class ConstraintResult:
@@ -29,8 +46,19 @@ class ConstraintResult:
 class ConstraintResolver:
     """Checks a Combination's entities for dependency contradictions."""
 
-    def __init__(self, mutex_registry: dict[str, list[set[str]]] | None = None) -> None:
+    def __init__(
+        self,
+        mutex_registry=None,
+        ambient_conditions=None,
+        category_severity=None,
+        deficit_threshold=None,
+    ) -> None:
         self.mutex = mutex_registry or MUTEX_VALUES
+        self.ambient = ambient_conditions or AMBIENT_CONDITIONS
+        self.category_severity = category_severity or CATEGORY_SEVERITY
+        self.deficit_threshold = (
+            deficit_threshold if deficit_threshold is not None else DEFICIT_THRESHOLD
+        )
 
     def resolve(self, combination: Combination) -> ConstraintResult:
         result = ConstraintResult()
@@ -42,7 +70,7 @@ class ConstraintResolver:
         self._check_requires_vs_excludes(all_deps, result)
         self._check_mutual_exclusion(all_deps, result)
         self._check_range_incompatibility(all_deps, result)
-        self._check_energy_density(combination, result)
+        self._check_provides_vs_range(combination, result)
         self._check_unmet_requirements(all_deps, result)
 
         if result.violations:
@@ -125,39 +153,39 @@ class ConstraintResolver:
                             f"but {max_name} limits {key} <= {max_val}"
                         )
 
-    def _check_energy_density(
+    def _check_provides_vs_range(
         self, combination: Combination, result: ConstraintResult
     ) -> None:
-        """Rule 6: If power source energy density << platform minimum → warn/block.
-
-        Uses a 25% threshold: below 25% of required → hard block (> 4x deficit).
-        """
-        density_provided: list[tuple[str, float]] = []
-        density_required: list[tuple[str, float]] = []
+        """Generic: provides(key, N) < range_min(key, M) → block/warn."""
+        provided: dict[str, list[tuple[str, float]]] = {}
+        required: dict[str, list[tuple[str, float]]] = {}
 
         for entity in combination.entities:
             for dep in entity.dependencies:
-                if dep.key == "energy_density" and dep.constraint_type == "provides":
-                    density_provided.append((entity.name, float(dep.value)))
-                elif dep.key == "energy_density" and dep.constraint_type == "range_min":
-                    density_required.append((entity.name, float(dep.value)))
+                try:
+                    val = float(dep.value)
+                except (ValueError, TypeError):
+                    continue
+                if dep.constraint_type == "provides":
+                    provided.setdefault(dep.key, []).append((entity.name, val))
+                elif dep.constraint_type == "range_min":
+                    required.setdefault(dep.key, []).append((entity.name, val))
 
-        for req_name, req_density in density_required:
-            if not density_provided:
-                continue  # No stored energy source in this combo — skip check
-            for prov_name, prov_density in density_provided:
-                if prov_density < req_density * 0.25:
-                    result.violations.append(
-                        f"{prov_name} provides {prov_density:.0f} J/kg but "
-                        f"{req_name} requires {req_density:.0f} J/kg "
-                        f"(energy density deficit > 4x)"
-                    )
-                elif prov_density < req_density:
-                    result.warnings.append(
-                        f"{prov_name} provides {prov_density:.0f} J/kg but "
-                        f"{req_name} requires {req_density:.0f} J/kg "
-                        f"(under-density)"
-                    )
+        for key in set(provided) & set(required):
+            for req_name, req_val in required[key]:
+                for prov_name, prov_val in provided[key]:
+                    if prov_val < req_val * self.deficit_threshold:
+                        result.violations.append(
+                            f"{prov_name} provides {key}={prov_val:.0f} but "
+                            f"{req_name} requires {key}>={req_val:.0f} "
+                            f"(deficit > {int(1 / self.deficit_threshold)}x)"
+                        )
+                    elif prov_val < req_val:
+                        result.warnings.append(
+                            f"{prov_name} provides {key}={prov_val:.0f} but "
+                            f"{req_name} requires {key}>={req_val:.0f} "
+                            f"(under-provision)"
+                        )
 
     def check_domain_constraints(
         self, combination: Combination, constraints: list[DomainConstraint]
@@ -181,31 +209,22 @@ class ConstraintResolver:
     def _check_unmet_requirements(
         self, all_deps: list[tuple[str, Dependency]], result: ConstraintResult
     ) -> None:
-        """Rule 5: Required condition not provided by any entity → conditional.
-
-        Energy-category requirements (e.g. energy_form) are hard blocks —
-        you cannot power an actuator with an incompatible energy source.
-        """
+        """Rule 5: Required condition not provided by any entity → conditional."""
         provides = {(d.key, d.value) for _, d in all_deps if d.constraint_type == "provides"}
-        # Ambient conditions that don't need to be explicitly provided
-        ambient = {
-            ("ground_surface", "true"),
-            ("gravity", "true"),
-            ("star_proximity", "true"),
-        }
 
         for name, dep in all_deps:
             if dep.constraint_type != "requires":
                 continue
-            if dep.category == "infrastructure":
-                continue  # Infrastructure is external, not checked here
+            severity = self.category_severity.get(dep.category, "warn")
+            if severity == "skip":
+                continue
             key_val = (dep.key, dep.value)
-            if key_val not in provides and key_val not in ambient:
+            if key_val not in provides and key_val not in self.ambient:
                 msg = (
                     f"{name} requires {dep.key}={dep.value} "
                     f"but no entity in this combination provides it"
                 )
-                if dep.category == "energy":
+                if severity == "block":
                     result.violations.append(msg)
                 else:
                     result.warnings.append(msg)
diff --git a/src/physcom/snapshot.py b/src/physcom/snapshot.py
new file mode 100644
index 0000000..df0483f
--- /dev/null
+++ b/src/physcom/snapshot.py
@@ -0,0 +1,312 @@
+"""Database snapshot export/import — JSON-based, uses natural keys."""
+
+from __future__ import annotations
+
+from datetime import datetime, timezone
+
+from physcom.db.repository import Repository
+from physcom.models.entity import Entity, Dependency
+from physcom.models.domain import Domain, DomainConstraint, MetricBound
+from physcom.models.combination import Combination
+
+
+def export_snapshot(repo: Repository) -> dict:
+    """Export the full database state to a portable dict (natural keys, no numeric IDs)."""
+    dimensions = repo.list_dimensions()
+    entities = repo.list_entities()
+    domains = repo.list_domains()
+    combinations = repo.list_combinations()
+
+    # Build entity id → (dimension, name) lookup
+    eid_to_ref: dict[int, list[str]] = {
+        e.id: [e.dimension, e.name] for e in entities
+    }
+
+    # Build metric id → name lookup
+    metric_rows = repo.conn.execute("SELECT id, name FROM metrics").fetchall()
+    mid_to_name: dict[int, str] = {r["id"]: r["name"] for r in metric_rows}
+
+    # Export dimensions
+    dim_list = [
+        {"name": d["name"], "description": d.get("description") or ""}
+        for d in dimensions
+    ]
+
+    # Export entities with dependencies
+    entity_list = []
+    for e in entities:
+        deps = []
+        for dep in e.dependencies:
+            deps.append({
+                "category": dep.category,
+                "key": dep.key,
+                "value": dep.value,
+                "unit": dep.unit,
+                "constraint_type": dep.constraint_type,
+            })
+        entity_list.append({
+            "name": e.name,
+            "dimension": e.dimension,
+            "description": e.description,
+            "dependencies": deps,
+        })
+
+    # Export domains with metric_bounds and constraints
+    domain_list = []
+    for d in domains:
+        mbs = []
+        for mb in d.metric_bounds:
+            mbs.append({
+                "metric_name": mb.metric_name,
+                "weight": mb.weight,
+                "norm_min": mb.norm_min,
+                "norm_max": mb.norm_max,
+                "unit": mb.unit,
+                "lower_is_better": mb.lower_is_better,
+            })
+        dcs = []
+        for dc in d.constraints:
+            dcs.append({
+                "key": dc.key,
+                "allowed_values": dc.allowed_values,
+            })
+        domain_list.append({
+            "name": d.name,
+            "description": d.description,
+            "metric_bounds": mbs,
+            "constraints": dcs,
+        })
+
+    # Export combinations
+    combo_list = []
+    for c in combinations:
+        entity_refs = [eid_to_ref[e.id] for e in c.entities if e.id in eid_to_ref]
+        combo_list.append({
+            "entity_refs": entity_refs,
+            "status": c.status,
+            "block_reason": c.block_reason,
+        })
+
+    # Export results and scores (per combo per domain)
+    result_list = []
+    score_list = []
+    domain_id_to_name: dict[int, str] = {d.id: d.name for d in domains}
+
+    for c in combinations:
+        for res in repo.get_results_for_combination(c.id):
+            domain_name = domain_id_to_name.get(res["domain_id"])
+            if not domain_name:
+                continue
+            entity_refs = [eid_to_ref[e.id] for e in c.entities if e.id in eid_to_ref]
+            result_list.append({
+                "entity_refs": entity_refs,
+                "domain": domain_name,
+                "composite_score": res["composite_score"],
+                "novelty_flag": res.get("novelty_flag"),
+                "llm_review": res.get("llm_review"),
+                "human_notes": res.get("human_notes"),
+                "pass_reached": res["pass_reached"],
+                "domain_block_reason": res.get("domain_block_reason"),
+            })
+
+            for sc in repo.get_combination_scores(c.id, res["domain_id"]):
+                score_list.append({
+                    "entity_refs": entity_refs,
+                    "domain": domain_name,
+                    "metric": mid_to_name.get(sc["metric_id"], ""),
+                    "raw_value": sc["raw_value"],
+                    "normalized_score": sc["normalized_score"],
+                    "estimation_method": sc.get("estimation_method"),
+                    "confidence": sc.get("confidence"),
+                })
+
+    return {
+        "version": 1,
+        "exported_at": datetime.now(timezone.utc).isoformat(),
+        "dimensions": dim_list,
+        "entities": entity_list,
+        "domains": domain_list,
+        "combinations": combo_list,
+        "results": result_list,
+        "scores": score_list,
+    }
+
+
+def import_snapshot(repo: Repository, data: dict, *, clear: bool = False) -> dict:
+    """Import a snapshot dict into the database.
+
+    Args:
+        repo: Target repository.
+        data: Snapshot dict (as produced by export_snapshot).
+        clear: If True, wipe all existing data before importing.
+
+    Returns:
+        Counts dict with keys: dimensions, entities, domains, combinations, results, scores.
+    """
+    if clear:
+        repo.clear_all()
+
+    counts = {
+        "dimensions": 0,
+        "entities": 0,
+        "domains": 0,
+        "combinations": 0,
+        "results": 0,
+        "scores": 0,
+    }
+
+    # 1. Dimensions
+    for d in data.get("dimensions", []):
+        repo.ensure_dimension(d["name"], d.get("description", ""))
+        counts["dimensions"] += 1
+
+    # 2. Entities (with dependencies)
+    for e_data in data.get("entities", []):
+        deps = [
+            Dependency(
+                category=dep["category"],
+                key=dep["key"],
+                value=dep["value"],
+                unit=dep.get("unit"),
+                constraint_type=dep.get("constraint_type", "requires"),
+            )
+            for dep in e_data.get("dependencies", [])
+        ]
+        existing = repo.get_entity_by_name(e_data["dimension"], e_data["name"])
+        if existing:
+            repo.replace_entity_dependencies(existing.id, deps)
+        else:
+            entity = Entity(
+                name=e_data["name"],
+                dimension=e_data["dimension"],
+                description=e_data.get("description", ""),
+                dependencies=deps,
+            )
+            repo.add_entity(entity)
+        counts["entities"] += 1
+
+    # 3. Domains (with metric_bounds and constraints)
+    for d_data in data.get("domains", []):
+        existing = repo.get_domain(d_data["name"])
+        if not existing:
+            mbs = [
+                MetricBound(
+                    metric_name=mb["metric_name"],
+                    weight=mb["weight"],
+                    norm_min=mb["norm_min"],
+                    norm_max=mb["norm_max"],
+                    unit=mb.get("unit", ""),
+                    lower_is_better=mb.get("lower_is_better", False),
+                )
+                for mb in d_data.get("metric_bounds", [])
+            ]
+            dcs = [
+                DomainConstraint(
+                    key=dc["key"],
+                    allowed_values=dc.get("allowed_values", []),
+                )
+                for dc in d_data.get("constraints", [])
+            ]
+            domain = Domain(
+                name=d_data["name"],
+                description=d_data.get("description", ""),
+                metric_bounds=mbs,
+                constraints=dcs,
+            )
+            repo.add_domain(domain)
+        counts["domains"] += 1
+
+    # Build lookup: (dimension, name) → entity id
+    all_entities = repo.list_entities()
+    ref_to_eid: dict[tuple[str, str], int] = {
+        (e.dimension, e.name): e.id for e in all_entities
+    }
+
+    # Build lookup: domain name → id
+    all_domains = repo.list_domains()
+    domain_name_to_id: dict[str, int] = {d.name: d.id for d in all_domains}
+
+    # Build lookup: metric name → id
+    metric_rows = repo.conn.execute("SELECT id, name FROM metrics").fetchall()
+    metric_name_to_id: dict[str, int] = {r["name"]: r["id"] for r in metric_rows}
+
+    # 4. Combinations
+    for c_data in data.get("combinations", []):
+        entity_refs = c_data.get("entity_refs", [])
+        entity_objs = []
+        skip = False
+        for ref in entity_refs:
+            eid = ref_to_eid.get((ref[0], ref[1]))
+            if eid is None:
+                skip = True
+                break
+            entity_objs.append(Entity(id=eid, name=ref[1], dimension=ref[0]))
+        if skip:
+            continue
+        combo = Combination(
+            entities=entity_objs,
+            status=c_data.get("status", "pending"),
+            block_reason=c_data.get("block_reason"),
+        )
+        repo.save_combination(combo)
+        counts["combinations"] += 1
+
+    # 5. Results
+    for r_data in data.get("results", []):
+        entity_refs = r_data.get("entity_refs", [])
+        entity_objs = []
+        skip = False
+        for ref in entity_refs:
+            eid = ref_to_eid.get((ref[0], ref[1]))
+            if eid is None:
+                skip = True
+                break
+            entity_objs.append(Entity(id=eid, name=ref[1], dimension=ref[0]))
+        if skip:
+            continue
+        combo = Combination(entities=entity_objs)
+        combo = repo.save_combination(combo)
+        domain_id = domain_name_to_id.get(r_data["domain"])
+        if combo.id is None or domain_id is None:
+            continue
+        repo.save_result(
+            combo.id,
+            domain_id,
+            composite_score=r_data.get("composite_score", 0.0),
+            pass_reached=r_data.get("pass_reached", 0),
+            novelty_flag=r_data.get("novelty_flag"),
+            llm_review=r_data.get("llm_review"),
+            human_notes=r_data.get("human_notes"),
+            domain_block_reason=r_data.get("domain_block_reason"),
+        )
+        counts["results"] += 1
+
+    # 6. Scores
+    for s_data in data.get("scores", []):
+        entity_refs = s_data.get("entity_refs", [])
+        entity_objs = []
+        skip = False
+        for ref in entity_refs:
+            eid = ref_to_eid.get((ref[0], ref[1]))
+            if eid is None:
+                skip = True
+                break
+            entity_objs.append(Entity(id=eid, name=ref[1], dimension=ref[0]))
+        if skip:
+            continue
+        combo = Combination(entities=entity_objs)
+        combo = repo.save_combination(combo)
+        domain_id = domain_name_to_id.get(s_data["domain"])
+        metric_id = metric_name_to_id.get(s_data.get("metric", ""))
+        if combo.id is None or domain_id is None or metric_id is None:
+            continue
+        repo.save_scores(combo.id, domain_id, [{
+            "metric_id": metric_id,
+            "raw_value": s_data.get("raw_value"),
+            "normalized_score": s_data.get("normalized_score"),
+            "estimation_method": s_data.get("estimation_method"),
+            "confidence": s_data.get("confidence"),
+        }])
+        counts["scores"] += 1
+
+    return counts
diff --git a/src/physcom_web/routes/admin.py b/src/physcom_web/routes/admin.py
index 426d3df..6907726 100644
--- a/src/physcom_web/routes/admin.py
+++ b/src/physcom_web/routes/admin.py
@@ -2,9 +2,13 @@
 
 from __future__ import annotations
 
-from flask import Blueprint, flash, redirect, render_template, url_for
+import json
+
+from flask import Blueprint, flash, redirect, render_template, request, url_for
+from flask import Response
 
 from physcom.seed.transport_example import load_transport_seed
+from physcom.snapshot import export_snapshot, import_snapshot
 from physcom_web.app import get_repo
 
 bp = Blueprint("admin", __name__, url_prefix="/admin")
@@ -38,14 +42,50 @@ def reseed():
     return redirect(url_for("admin.admin_index"))
 
 
-@bp.route("/wipe-and-reseed", methods=["POST"])
-def wipe_and_reseed():
+@bp.route("/wipe", methods=["POST"])
+def wipe():
     repo = get_repo()
     repo.clear_all()
-    counts = load_transport_seed(repo)
-    total = counts["platforms"] + counts["actuators"] + counts["energy_storages"]
+    flash("Wiped all data.", "success")
+    return redirect(url_for("admin.admin_index"))
+
+
+@bp.route("/snapshot/export")
+def snapshot_export():
+    repo = get_repo()
+    data = export_snapshot(repo)
+    body = json.dumps(data, indent=2)
+    return Response(
+        body,
+        mimetype="application/json",
+        headers={"Content-Disposition": "attachment; filename=physcom_snapshot.json"},
+    )
+
+
+@bp.route("/snapshot/import", methods=["POST"])
+def snapshot_import():
+    repo = get_repo()
+    clear = "clear" in request.form
+
+    file = request.files.get("file")
+    if not file or not file.filename:
+        flash("No file selected.", "error")
+        return redirect(url_for("admin.admin_index"))
+
+    try:
+        raw = file.read().decode("utf-8")
+        data = json.loads(raw)
+    except (UnicodeDecodeError, json.JSONDecodeError) as exc:
+        flash(f"Invalid JSON file: {exc}", "error")
+        return redirect(url_for("admin.admin_index"))
+
+    counts = import_snapshot(repo, data, clear=clear)
+    mode = "Cleared DB and imported" if clear else "Merged"
     flash(
-        f"Wiped all data and reseeded — {total} entities, {counts['domains']} domains.",
+        f"{mode} snapshot — {counts['dimensions']} dimensions, "
+        f"{counts['entities']} entities, {counts['domains']} domains, "
+        f"{counts['combinations']} combinations, {counts['results']} results, "
+        f"{counts['scores']} scores.",
         "success",
     )
     return redirect(url_for("admin.admin_index"))
diff --git a/src/physcom_web/templates/admin/index.html b/src/physcom_web/templates/admin/index.html
index 8c7f1c8..9746f34 100644
--- a/src/physcom_web/templates/admin/index.html
+++ b/src/physcom_web/templates/admin/index.html
@@ -37,14 +37,49 @@
   </div>
 
   <div class="card warning-box">
-    <h3>Wipe &amp; Reseed</h3>
+    <h3>Wipe All Data</h3>
     <p class="subtitle">
       Delete <strong>all</strong> data — entities, domains, combinations,
-      pipeline runs — then reload seed data from scratch.
+      pipeline runs. Use Reseed afterwards to restore seed data.
     </p>
-    <form method="post" action="{{ url_for('admin.wipe_and_reseed') }}" style="margin-top: 0.75rem"
-          onsubmit="return confirm('This will permanently delete ALL data and reseed from scratch. Continue?')">
-      <button type="submit" class="btn btn-danger">Wipe &amp; Reseed</button>
+    <form method="post" action="{{ url_for('admin.wipe') }}" style="margin-top: 0.75rem"
+          onsubmit="return confirm('This will permanently delete ALL data. Continue?')">
+      <button type="submit" class="btn btn-danger">Wipe</button>
+    </form>
+  </div>
+</div>
+
+<h2>Snapshots</h2>
+<div class="card-grid">
+  <div class="card">
+    <h3>Export Snapshot</h3>
+    <p class="subtitle">
+      Download the full database state as a JSON file — entities,
+      domains, combinations, results, and scores.
+    </p>
+    <div style="margin-top: 0.75rem">
+      <a href="{{ url_for('admin.snapshot_export') }}" class="btn btn-primary">Download JSON</a>
+    </div>
+  </div>
+
+  <div class="card">
+    <h3>Import Snapshot</h3>
+    <p class="subtitle">
+      Upload a previously exported JSON snapshot. Merge adds new data
+      alongside existing; clear wipes everything first.
+    </p>
+    <form method="post" action="{{ url_for('admin.snapshot_import') }}"
+          enctype="multipart/form-data" style="margin-top: 0.75rem">
+      <div class="form-group">
+        <input type="file" name="file" accept=".json" required>
+      </div>
+      <div style="display: flex; align-items: center; gap: 0.75rem">
+        <button type="submit" class="btn btn-primary">Import (Merge)</button>
+        <button type="submit" name="clear" value="1" class="btn btn-danger"
+                onclick="return confirm('This will wipe ALL existing data before importing. Continue?')">
+          Import (Clear &amp; Replace)
+        </button>
+      </div>
     </form>
   </div>
 </div>
diff --git a/tests/test_constraint_resolver.py b/tests/test_constraint_resolver.py
index eec4975..ce8e1c7 100644
--- a/tests/test_constraint_resolver.py
+++ b/tests/test_constraint_resolver.py
@@ -97,7 +97,7 @@ def test_energy_density_deficit_blocks():
     combo = Combination(entities=[platform, storage])
     result = resolver.resolve(combo)
     assert result.status == "p1_fail"
-    assert any("energy density deficit" in v for v in result.violations)
+    assert any("deficit" in v for v in result.violations)
 
 
 def test_energy_density_under_density_warning():
@@ -118,7 +118,7 @@ def test_energy_density_under_density_warning():
     combo = Combination(entities=[platform, storage])
     result = resolver.resolve(combo)
     assert result.status != "p1_fail"
-    assert any("under-density" in w for w in result.warnings)
+    assert any("under-provision" in w for w in result.warnings)
 
 
 def test_energy_density_no_constraint_if_no_provider():
@@ -139,7 +139,7 @@ def test_energy_density_no_constraint_if_no_provider():
     resolver = ConstraintResolver()
     combo = Combination(entities=[platform, actuator])
     result = resolver.resolve(combo)
-    density_violations = [v for v in result.violations if "energy density" in v]
+    density_violations = [v for v in result.violations if "energy_density" in v]
     assert len(density_violations) == 0
 
 
diff --git a/tests/test_snapshot.py b/tests/test_snapshot.py
new file mode 100644
index 0000000..c8612ae
--- /dev/null
+++ b/tests/test_snapshot.py
@@ -0,0 +1,207 @@
+"""Tests for snapshot export/import."""
+
+from __future__ import annotations
+
+import pytest
+
+from physcom.db.schema import init_db
+from physcom.db.repository import Repository
+from physcom.models.entity import Entity, Dependency
+from physcom.models.domain import Domain, DomainConstraint, MetricBound
+from physcom.models.combination import Combination
+from physcom.snapshot import export_snapshot, import_snapshot
+
+
+def test_export_roundtrip(seeded_repo, tmp_path):
+    """Export from seeded_repo, import into fresh repo, verify counts match."""
+    data = export_snapshot(seeded_repo)
+
+    # Fresh repo
+    conn = init_db(tmp_path / "fresh.db")
+    fresh = Repository(conn)
+
+    counts = import_snapshot(fresh, data, clear=True)
+
+    assert counts["dimensions"] == len(data["dimensions"])
+    assert counts["entities"] == len(data["entities"])
+    assert counts["domains"] == len(data["domains"])
+
+    # Verify actual DB contents match
+    assert len(fresh.list_dimensions()) == len(seeded_repo.list_dimensions())
+    assert len(fresh.list_entities()) == len(seeded_repo.list_entities())
+    assert len(fresh.list_domains()) == len(seeded_repo.list_domains())
+
+
+def test_export_contains_entities(seeded_repo):
+    """Exported data has expected entity structure."""
+    data = export_snapshot(seeded_repo)
+
+    assert data["version"] == 1
+    assert "exported_at" in data
+
+    entity_names = {e["name"] for e in data["entities"]}
+    # Transport seed should include at least these
+    assert "Bicycle" in entity_names or len(entity_names) > 0
+
+    # Each entity has the right keys
+    for e in data["entities"]:
+        assert "name" in e
+        assert "dimension" in e
+        assert "description" in e
+        assert "dependencies" in e
+        assert isinstance(e["dependencies"], list)
+
+
+def test_export_contains_domains(seeded_repo):
+    """Exported domains have metric_bounds and constraints."""
+    data = export_snapshot(seeded_repo)
+
+    assert len(data["domains"]) > 0
+    for d in data["domains"]:
+        assert "name" in d
+        assert "metric_bounds" in d
+        assert "constraints" in d
+        for mb in d["metric_bounds"]:
+            assert "metric_name" in mb
+            assert "weight" in mb
+            assert "norm_min" in mb
+            assert "norm_max" in mb
+
+
+def test_import_clear_mode(seeded_repo, tmp_path):
+    """Import with clear=True wipes old data and loads new."""
+    # Export seeded data
+    data = export_snapshot(seeded_repo)
+
+    # Create a second repo with its own data
+    conn = init_db(tmp_path / "other.db")
+    other = Repository(conn)
+    other.add_entity(Entity(
+        name="Zeppelin",
+        dimension="platform",
+        description="Lighter-than-air craft",
+    ))
+
+    assert other.get_entity_by_name("platform", "Zeppelin") is not None
+
+    # Import with clear — old data should be gone
+    import_snapshot(other, data, clear=True)
+
+    assert other.get_entity_by_name("platform", "Zeppelin") is None
+    assert len(other.list_entities()) == len(data["entities"])
+
+
+def test_import_merge_replaces_deps(repo):
+    """Merge import replaces dependencies on existing entities."""
+    # Add an entity with one dep
+    entity = Entity(
+        name="Widget",
+        dimension="gadget",
+        description="A test widget",
+        dependencies=[
+            Dependency("physical", "mass", "10", "kg", "range_min"),
+        ],
+    )
+    repo.add_entity(entity)
+    assert len(repo.get_entity_by_name("gadget", "Widget").dependencies) == 1
+
+    # Build snapshot with different deps for that entity
+    data = {
+        "version": 1,
+        "exported_at": "2026-01-01T00:00:00+00:00",
+        "dimensions": [{"name": "gadget", "description": ""}],
+        "entities": [{
+            "name": "Widget",
+            "dimension": "gadget",
+            "description": "A test widget",
+            "dependencies": [
+                {"category": "physical", "key": "mass", "value": "50",
+                 "unit": "kg", "constraint_type": "range_min"},
+                {"category": "energy", "key": "energy_form", "value": "electric",
+                 "unit": None, "constraint_type": "requires"},
+            ],
+        }],
+        "domains": [],
+        "combinations": [],
+        "results": [],
+        "scores": [],
+    }
+
+    counts = import_snapshot(repo, data)
+
+    widget = repo.get_entity_by_name("gadget", "Widget")
+    assert len(widget.dependencies) == 2
+    dep_keys = {(d.category, d.key) for d in widget.dependencies}
+    assert ("physical", "mass") in dep_keys
+    assert ("energy", "energy_form") in dep_keys
+
+
+def test_import_with_combinations(seeded_repo, tmp_path):
+    """Export combos+results from a pipeline run, import into fresh DB."""
+    # Run pipeline to generate combos and results
+    from physcom.engine.constraint_resolver import ConstraintResolver
+    from physcom.engine.scorer import Scorer
+    from physcom.engine.pipeline import Pipeline
+    from physcom.llm.providers.mock import MockLLMProvider
+
+    domain = seeded_repo.get_domain("urban_commuting")
+    resolver = ConstraintResolver()
+    scorer = Scorer(domain)
+    pipeline = Pipeline(seeded_repo, resolver, scorer, llm=MockLLMProvider())
+    pipeline.run(domain, ["platform", "actuator", "energy_storage"],
+                 score_threshold=0.0, passes=[1, 2, 3])
+
+    # Export
+    data = export_snapshot(seeded_repo)
+    assert len(data["combinations"]) > 0
+    assert len(data["results"]) > 0
+
+    # Import into fresh DB
+    conn = init_db(tmp_path / "fresh.db")
+    fresh = Repository(conn)
+    counts = import_snapshot(fresh, data, clear=True)
+
+    assert counts["combinations"] > 0
+    assert counts["results"] > 0
+
+    # Verify some results are present in the fresh DB
+    fresh_combos = fresh.list_combinations()
+    assert len(fresh_combos) == len(data["combinations"])
+
+
+def test_import_merge_skips_existing_domain(repo):
+    """Merge import skips domains that already exist."""
+    domain = Domain(
+        name="test_domain",
+        description="Original description",
+        metric_bounds=[
+            MetricBound("speed", weight=1.0, norm_min=0, norm_max=100),
+        ],
+    )
+    repo.add_domain(domain)
+
+    data = {
+        "version": 1,
+        "exported_at": "2026-01-01T00:00:00+00:00",
+        "dimensions": [],
+        "entities": [],
+        "domains": [{
+            "name": "test_domain",
+            "description": "Updated description",
+            "metric_bounds": [
+                {"metric_name": "speed", "weight": 0.5, "norm_min": 0,
+                 "norm_max": 200, "unit": "", "lower_is_better": False},
+            ],
+            "constraints": [],
+        }],
+        "combinations": [],
+        "results": [],
+        "scores": [],
+    }
+
+    import_snapshot(repo, data)
+
+    # Domain should keep original description (merge skips existing)
+    d = repo.get_domain("test_domain")
+    assert d.description == "Original description"
+    assert d.metric_bounds[0].weight == 1.0