@@ -585,3 +585,65 @@ authentication, lifecycle/PIT, financial admission and trading remain false.
 Existing period and cash operations are unchanged; old providers reject this
 new schema. App/Lark interaction, source-consumer adoption and financial utility
 are independent remaining qualifications.
+
+# Stock instant change (extension 0.8.12)
+
+`finance_stock_change_input_v1` explicitly compares stocks. The root contains
+exactly `schema_version`, `later`, `earlier`, and `compatibility`. Each operand
+contains `source_digest`, original nullable `context`, nullable `point`, the
+existing nullable eight-field `statement_basis`, `aggregation_kind`, and
+`accuracy`. The shared temporal vocabulary is unchanged; only `stock` qualifies.
+
+A point has exactly `context_source_digest`, `evidence_ref`, `role`, and
+`instant`. References/digests retain the existing period owner's bounds.
+`instant` is null or an explicit dateTime; the economic role is an exact token.
+The original context must encode an instant with a known timezone, and its
+normalized boundary must equal the declared point. XBRL date-only end-of-day
+conversion and offsets reuse `assess_period_encoding`; column labels cannot
+supply absent original context or timezone. The earlier point must be strictly
+before the later one; equal or reversed instants refuse a qualified change.
+These are balance instants, not new first-public or observation clocks.
+
+Subjects, declared metrics and currency/scale units must match. Distinct column
+scopes can belong to one source/filing/version. Other source/version joins need
+explicit `compatibility` with exactly `evidence_ref`, `later`, and `earlier`;
+each pin contains the exact current `source_digest`, `filing_ref`, `version_ref`,
+and `scope_ref`. This reuses the cumulative-flow version-compatibility owner.
+Neither matching names nor matching numbers proves scope comparability or
+completeness. A producer owns those meanings, withdrawals and conflicts.
+
+The v1 requires producer-declared exact accuracy for both amounts. Finite or
+missing precision remains visible and holds the qualified change. There is no
+implicit rounding policy, token-quantity unit conversion or inferred cash
+identity. Unknown unit does not become USD, and a composite metric does not
+become pure cash. Different metrics/subjects/units and nonstocks suppress even
+the diagnostic candidate.
+
+`finance_stock_change_assessment_v1` retains original operands, point and
+accuracy assessments, current compatibility pins, canonical input digest and
+sorted reasons. `candidate_lexical_difference` is diagnostic bounded Decimal
+subtraction when the declared stock identities and amounts are known.
+`stock_change` and `change_window` are emitted only when
+`change_evidence_eligible` is true. A window records two instants, not a duration
+flow. `cash_flow_derived` and `causes_of_change_assessed` are always false:
+stock change cannot establish acquisitions, financing, spending or its causes.
+Source authentication, lifecycle/PIT, financial admission and trading also
+remain false. Upstream source admission remains independent.
+
+```sh
+loopx-finance-value-discovery assess-stock-change \
+  --input-json packages/loopx-finance-value-discovery/examples/stock-change-v1.json
+```
+
+The same schema selects this operation on the installed provider's stdin
+runtime. Missing evidence is a successful assessment with a held result;
+malformed closed shapes use the existing error packet/nonzero exit. Optional
+provider lifecycle remains unchanged. Disable through `loopx extension disable
+loopx-finance-value-discovery --execute`; rollback uses the prior provider and
+its original input versions. Old providers reject the new schema, while old
+cash, duration comparison v1/v2, and flow difference v1 inputs keep their
+original behavior and replay clocks. No new catalog or Core authority exists.
+
+This stage delivers CLI/runtime computation. Its App/Lark interaction and the
+source provider's production consumer are still companion qualifications;
+installation and this calculation do not establish financial utility.
@@ -0,0 +1,62 @@
+{
+  "schema_version": "finance_stock_change_input_v1",
+  "compatibility": null,
+  "later": {
+    "source_digest": "sha256:dddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd",
+    "context": {
+      "instant": "2002-12-31Z"
+    },
+    "point": {
+      "context_source_digest": "sha256:dddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd",
+      "evidence_ref": "synthetic:point:later",
+      "role": "balance_sheet",
+      "instant": "2003-01-01T00:00:00Z"
+    },
+    "statement_basis": {
+      "subject_ref": "synthetic:issuer",
+      "metric_ref": "cash_and_equivalents",
+      "filing_ref": "synthetic:filing",
+      "version_ref": "synthetic:v1",
+      "scope_ref": "synthetic:column:later",
+      "evidence_ref": "synthetic:row:later",
+      "unit": {
+        "currency": "USD",
+        "scale": 6
+      },
+      "value": "123.50"
+    },
+    "aggregation_kind": "stock",
+    "accuracy": {
+      "decimals": "INF"
+    }
+  },
+  "earlier": {
+    "source_digest": "sha256:dddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd",
+    "context": {
+      "instant": "2001-12-31Z"
+    },
+    "point": {
+      "context_source_digest": "sha256:dddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddddd",
+      "evidence_ref": "synthetic:point:earlier",
+      "role": "balance_sheet",
+      "instant": "2002-01-01T00:00:00Z"
+    },
+    "statement_basis": {
+      "subject_ref": "synthetic:issuer",
+      "metric_ref": "cash_and_equivalents",
+      "filing_ref": "synthetic:filing",
+      "version_ref": "synthetic:v1",
+      "scope_ref": "synthetic:column:earlier",
+      "evidence_ref": "synthetic:row:earlier",
+      "unit": {
+        "currency": "USD",
+        "scale": 6
+      },
+      "value": "100.25"
+    },
+    "aggregation_kind": "stock",
+    "accuracy": {
+      "decimals": "INF"
+    }
+  }
+}
@@ -1,6 +1,6 @@
 schema_version = "loopx_extension_manifest_v0"
 id = "loopx-finance-value-discovery"
-version = "0.8.11"
+version = "0.8.12"
 requires_loopx_api = ">=1,<2"
 permissions = []
 
 
@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "loopx-finance-value-discovery"
-version = "0.8.11"
+version = "0.8.12"
 description = "Public-safe finance value-discovery extension for LoopX."
 readme = "README.md"
 requires-python = ">=3.11"
 
@@ -2,6 +2,12 @@
 
 from importlib import import_module
 
+from .stock_change import (
+    FINANCE_STOCK_CHANGE_INPUT_SCHEMA_VERSION,
+    FINANCE_STOCK_CHANGE_SCHEMA_VERSION,
+    assess_stock_change,
+)
+
 from .cumulative_flow import (
     FINANCE_FLOW_DIFFERENCE_INPUT_SCHEMA_VERSION,
     FINANCE_FLOW_DIFFERENCE_SCHEMA_VERSION,
@@ -87,6 +93,8 @@
     "FINANCE_CASH_RECONCILIATION_SCHEMA_VERSION",
     "FINANCE_CONTRACT_LIQUIDITY_EVALUATION_SCHEMA_VERSION",
     "FINANCE_CONTRACT_LIQUIDITY_INPUT_SCHEMA_VERSION",
+    "FINANCE_STOCK_CHANGE_INPUT_SCHEMA_VERSION",
+    "FINANCE_STOCK_CHANGE_SCHEMA_VERSION",
     "FINANCE_FLOW_DIFFERENCE_INPUT_SCHEMA_VERSION",
     "FINANCE_FLOW_DIFFERENCE_SCHEMA_VERSION",
     "FINANCE_METRIC_PACK_EVALUATION_SCHEMA_VERSION",
@@ -111,6 +119,7 @@
     "build_finance_transaction_approval_packet",
     "build_finance_value_discovery_packet",
     "assess_numeric_accuracy",
+    "assess_stock_change",
     "assess_flow_difference",
     "assess_cash_reconciliation",
     "assess_period_comparison",
 
@@ -56,6 +56,11 @@
     assess_flow_difference,
 )
 
+from .stock_change import (
+    FINANCE_STOCK_CHANGE_INPUT_SCHEMA_VERSION,
+    assess_stock_change,
+)
+
 FINANCE_RESEARCH_DASHBOARD_INPUT_SCHEMA_VERSION = "finance_research_dashboard_input_v0"
 
 
@@ -106,6 +111,11 @@ def _direct_parser() -> argparse.ArgumentParser:
         help="Derive a tail flow from compatible cumulative/prefix declarations.",
     )
     flow_parser.add_argument("--input-json", required=True)
+    stock_parser = sub.add_parser(
+        "assess-stock-change",
+        help="Compare ordered stock instants; never derive a cash flow.",
+    )
+    stock_parser.add_argument("--input-json", required=True)
     cash_parser = sub.add_parser(
         "assess-cash",
         help="Reconcile six source-column signed cash amounts and retain unknowns.",
@@ -216,6 +226,8 @@ def run(argv: Sequence[str] | None = None) -> int:
             schema_version = payload.get("schema_version")
             if schema_version == FINANCE_CASH_RECONCILIATION_INPUT_SCHEMA_VERSION:
                 packet = assess_cash_reconciliation(payload)
+            elif schema_version == FINANCE_STOCK_CHANGE_INPUT_SCHEMA_VERSION:
+                packet = assess_stock_change(payload)
             elif schema_version == FINANCE_FLOW_DIFFERENCE_INPUT_SCHEMA_VERSION:
                 packet = assess_flow_difference(payload)
             elif schema_version in {
@@ -256,6 +268,8 @@ def run(argv: Sequence[str] | None = None) -> int:
     try:
         if args.command == "assess-period":
             packet = assess_period_comparison(_load_json(args.input_json))
+        elif args.command == "assess-stock-change":
+            packet = assess_stock_change(_load_json(args.input_json))
         elif args.command == "assess-period-difference":
             packet = assess_flow_difference(_load_json(args.input_json))
         elif args.command == "assess-cash":
@@ -326,7 +340,7 @@ def run(argv: Sequence[str] | None = None) -> int:
                 "replay-beta, evaluate-pack, replay-pack, list-packs, "
                 "render-lark-card, build-operation-request, or "
                 "evaluate-contract-liquidity, evaluate-position, assess-period, "
-                "assess-period-difference, or assess-cash"
+                "assess-period-difference, assess-stock-change, or assess-cash"
             )
     except Exception as exc:
         # Position inputs are private; malformed values never enter diagnostics.
 
@@ -13,19 +13,18 @@
 from enum import StrEnum
 from typing import Any
 
-from .cash_reconciliation import _encoded, _fields, _number, _text
+from .cash_reconciliation import _encoded, _fields, _number
 from .numeric_accuracy import NumericAccuracyState
 from .period_semantics import (
     FINANCE_PERIOD_COMPARISON_INPUT_SCHEMA_VERSION,
     assess_period_comparison,
 )
 from .replay import canonical_sha256
-from .statement_basis import _basis
+from .statement_basis import _basis, _version_compatibility
 
 FINANCE_FLOW_DIFFERENCE_INPUT_SCHEMA_VERSION = "finance_flow_difference_input_v1"
 FINANCE_FLOW_DIFFERENCE_SCHEMA_VERSION = "finance_flow_difference_assessment_v1"
 _PERIOD_FIELDS = {"source_digest", "context", "economic_period"}
-_PIN_FIELDS = {"source_digest", "filing_ref", "version_ref", "scope_ref"}
 
 
 class TemporalAggregationKind(StrEnum):
@@ -37,49 +36,6 @@ class TemporalAggregationKind(StrEnum):
     RATIO = "ratio"
 
 
-def _compatibility(
-    declaration: Any,
-    operands: Mapping[str, Any],
-    bases: Mapping[str, Any],
-    reasons: set[str],
-) -> None:
-    if declaration is None:
-        # Distinct period columns may share one filing/version. Scope is retained
-        # in lineage; it is not expected to be the same column on both sides.
-        total, prefix = bases["total"], bases["prefix"]
-        if (
-            total is None
-            or prefix is None
-            or any(
-                total[field] is None or total[field] != prefix[field]
-                for field in ("filing_ref", "version_ref")
-            )
-            or operands["total"]["source_digest"] != operands["prefix"]["source_digest"]
-        ):
-            reasons.add("source_version_compatibility_missing")
-        return
-    declaration = _fields(
-        declaration, {"evidence_ref", "total", "prefix"}, "flow compatibility"
-    )
-    if declaration["evidence_ref"] is None:
-        reasons.add("compatibility_evidence_missing")
-    else:
-        _text(declaration["evidence_ref"], "compatibility evidence_ref")
-    for side in ("total", "prefix"):
-        pin = _fields(declaration[side], _PIN_FIELDS, "flow compatibility pin")
-        for field in _PIN_FIELDS:
-            if pin[field] is None:
-                reasons.add(f"{side}_compatibility_{field}_missing")
-            else:
-                _text(pin[field], field)
-            expected = (
-                operands[side][field]
-                if field == "source_digest"
-                else (bases[side][field] if bases[side] is not None else None)
-            )
-            if expected is None or pin[field] != expected:
-                reasons.add(f"{side}_compatibility_{field}_mismatch")
-
 
 def assess_flow_difference(payload: Mapping[str, Any]) -> dict[str, Any]:
     """Subtract a prefix only after declared flow/identity/period/accuracy gates.
@@ -149,7 +105,7 @@ def assess_flow_difference(payload: Mapping[str, Any]) -> dict[str, Any]:
             ):
                 reasons.add(f"flow_{field}_mismatch")
                 identity_matches = False
-    _compatibility(payload["compatibility"], operands, bases, reasons)
+    _version_compatibility(payload["compatibility"], operands, bases, reasons)
 
     tail = None
     left, right = period["operands"]["left"], period["operands"]["right"]
 
@@ -54,6 +54,54 @@ def _basis(value: Any, side: str, reasons: set[str]) -> Mapping[str, Any] | None
     return basis
 
 
+
+def _version_compatibility(
+    declaration: Any,
+    operands: Mapping[str, Any],
+    bases: Mapping[str, Any],
+    reasons: set[str],
+    *,
+    sides: tuple[str, str] = ("total", "prefix"),
+) -> None:
+    if declaration is None:
+        # Distinct period columns may share one filing/version. Scope is retained
+        # in lineage; it is not expected to be the same column on both sides.
+        left, right = sides
+        total, prefix = bases[left], bases[right]
+        if (
+            total is None
+            or prefix is None
+            or any(
+                total[field] is None or total[field] != prefix[field]
+                for field in ("filing_ref", "version_ref")
+            )
+            or operands[left]["source_digest"] != operands[right]["source_digest"]
+        ):
+            reasons.add("source_version_compatibility_missing")
+        return
+    declaration = _fields(
+        declaration, {"evidence_ref", *sides}, "source compatibility"
+    )
+    if declaration["evidence_ref"] is None:
+        reasons.add("compatibility_evidence_missing")
+    else:
+        _text(declaration["evidence_ref"], "compatibility evidence_ref")
+    for side in sides:
+        pin = _fields(declaration[side], _PIN_FIELDS, "source compatibility pin")
+        for field in _PIN_FIELDS:
+            if pin[field] is None:
+                reasons.add(f"{side}_compatibility_{field}_missing")
+            else:
+                _text(pin[field], field)
+            expected = (
+                operands[side][field]
+                if field == "source_digest"
+                else (bases[side][field] if bases[side] is not None else None)
+            )
+            if expected is None or pin[field] != expected:
+                reasons.add(f"{side}_compatibility_{field}_mismatch")
+
+
 def _component_refs(value: Any, name: str) -> list[str]:
     if not isinstance(value, list) or not 1 <= len(value) <= 32:
         raise ValueError(f"{name} requires 1..32 unique component references")