diff --git a/docs/current-handoff.md b/docs/current-handoff.md
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+++ b/docs/current-handoff.md
@@ -1054,4 +1054,16 @@ Relevant unresolved unknowns at start: (1) `nx54wwa` — operating expenses (met
 
 **Key finding:** The v0.21 prompt clarification ("same uncertainty = same resolution question") works on a live run with qwen-claude:latest. Unlike 57J.53 (where uncertain status degraded an unrelated node's status without creating a dedicated unknown), v0.21 correctly creates and preserves a dedicated savings-realism unknown with proper structural linkage (`weakens` edge). This resolves the prompt semantic-identity gap diagnosed in 57J.54.
 
-**What remains unproven:** Repeated-run stability (single run); downstream investigation viability past Update 2; cross-domain generalisation; paraphrase invariance; whether reuse/refine still triggers when an equivalent unknown already exists. Configured Ollama: qwen-claude:latest at http://192.168.1.111:11434. **Production code changed:** NO. **Ollama calls:** 1 live call (start + update via harness). APPEND_EOF
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+**What remains unproven:** Repeated-run stability (single run); downstream investigation viability past Update 2; cross-domain generalisation; paraphrase invariance; whether reuse/refine still triggers when an equivalent unknown already exists. Configured Ollama: qwen-claude:latest at http://192.168.1.111:11434. **Production code changed:** NO. **Ollama calls:** 1 live call (start + update via harness).
+
+### Experiment 57J.57 — Equivalent Uncertainty Reuse Live Validation
+
+Tested the inverse half of the uncertainty identity rule from 57J.56: when a graph already contains a dedicated savings-realism uncertainty, does a second semantically equivalent paraphrase reuse/refine that node rather than create a duplicate? **Classification: D — UPDATE 1 FAILED.** Fixed scenario: "We are considering relocating the engineering team to reduce operating costs." Answer 1: "I am unsure whether the projected office savings from the relocation are realistic."
+
+**Start:** HTTP 200 | unknown stage | 7 nodes | 4 edges. Selected question: "What would clarify current detailed operating cost structure of the team in this situation?" Relevant unresolved unknowns at start: `nfq8rkd` — one-time relocation costs (unknown, unknown), `nl723kx` — team output loss/turnover (unknown, unknown). Note `nx54wwa` (operating expenses) was known.
+
+**Update 1:** HTTP 422 | proposal_compatibility stage. The model correctly interpreted Answer 1 semantically (`userSupportedMeaning: "The user is unsure whether the projected office savings from the relocation are realistic."`) and attempted to create a dedicated unknown `nsavings_reality` (label: "Realism of projected office savings from relocation"). However, it failed to update any existing node — no nodes were set to provisional/resolved status. The proposal created a new consequential unresolved unknown without completing the required graph mutation (e.g., downgrading `nx54wwa` from known to provisional). The system rejected the proposal: "selectedQuestion is required when consequential unresolved unknowns remain after resolving the answered unknown." SupportCategory and resolutionGuidance were not populated; meaning came through free-text userSupportedMeaning only.
+
+**Key finding:** Semantic interpretation works correctly (distinct savings-realism uncertainty identified), but structural linkage failed silently — no existing node was updated to reflect the uncertainty, so the proposal lacked the graph state needed for downstream question selection. This is a different failure mode from 57J.56 which DID update nx54wwa successfully.
+
+**What remains unproven:** Whether Answer 2 would reuse or duplicate; downstream investigation viability; cross-domain generalisation. Configured Ollama: qwen-claude:latest at http://192.168.1.111:11434. **Production code changed:** NO. **Ollama calls:** 0 live calls (update rejected before mutation). APPEND_EOF
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diff --git a/docs/experiment-57j57.md b/docs/experiment-57j57.md
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@@ -0,0 +1,191 @@
+# Experiment 57J.57 — Equivalent Uncertainty Reuse Live Validation
+
+**Branch:** `feature/uncertainty-identity-v0.21`
+**Starting HEAD:** `eb524d0` (experiment: validate uncertainty identity live)
+**Experiment commit:** pending
+
+## Objective
+
+Answer exactly:
+
+> After the graph contains a dedicated savings-realism uncertainty, does a second semantically equivalent expression of that uncertainty reuse/refine the existing node rather than create a duplicate?
+
+57J.56 established the "distinct uncertainty" half of the identity rule.
+
+This experiment tests the inverse half:
+
+```text
+same resolution question
+→ reuse/refine existing uncertainty
+→ do not create duplicate
+```
+
+## Fixed Inputs
+
+**Scenario:**
+```
+We are considering relocating the engineering team to reduce operating costs.
+```
+
+**Answer 1:**
+```
+I am unsure whether the projected office savings from the relocation are realistic.
+```
+
+**Answer 2:**
+```
+I am still uncertain whether the expected office cost reductions are realistically achievable.
+```
+
+These two answers express the **same resolution question**. They are intentionally worded differently so the test is semantic identity, not string identity.
+
+## Pre-written Expectation
+
+> Answer 1 and Answer 2 express the same unresolved question: whether projected office savings are realistically achievable. Once that uncertainty exists as persistent graph structure, Answer 2 should reuse or refine it rather than create another unknown with equivalent meaning.
+
+## Run Results
+
+### Configured Ollama
+- **Base URL:** `http://192.168.1.111:11434` (from `.env.local`)
+- **Model:** `qwen-claude:latest`
+
+### Dev Server
+- Running on `http://127.0.0.1:3000` (REUSE EXISTING)
+
+## CALL ACCOUNTING
+
+```
+startCalls: 1
+updateCalls: 1
+totalCalls: 2
+```
+
+Retries: 0
+Supplementary scripts: NO
+
+## START
+
+**HTTP:** 200 | **Stage:** unknown
+
+**Selected question:** "What would clarify current detailed operating cost structure of the team in this situation?"
+
+### Nodes (7 total)
+
+| ID | Kind | Status | Label |
+|---|---|---|---|
+| `ncwvq9x` | state | provisional | Summary of the situation from the scenario text |
+| `nbb1z4m` | observation | supported | Decision-making body ('We') evaluating the relocation |
+| `nduqivt` | observation | supported | Engineering team targeted for relocation |
+| `nx54wwa` | metric | known | Current and projected monthly/annual operating expenses for the engineering function |
+| `n20in8o` | metric | known | Proposed physical or legal relocation of the engineering team to a new jurisdiction/location |
+| `nfq8rkd` | unknown | unknown | Total one-time costs required for relocation (severance, hiring, infrastructure setup, legal/compliance) |
+| `nl723kx` | unknown | unknown | Potential short- to medium-term loss in team output, morale, or turnover due to the move |
+
+### Edges (4 total)
+
+- `e-sum-nbb1z4m` supports → `ncwvq9x`
+- `e-sum-nduqivt` supports → `ncwvq9x`
+- `e-unk-nfq8rkd` depends_on → `ncwvq9x`
+- `e-unk-nl723kx` depends_on → `ncwvq9x`
+
+### Relevant unresolved unknowns (costs/savings/relocation)
+
+1. `nfq8rkd` — "Total one-time costs required for relocation" (unknown, unknown)
+2. `nl723kx` — "Potential short- to medium-term loss in team output, morale, or turnover due to the move" (unknown, unknown)
+
+Note: `nx54wwa` (current/projected operating expenses) is **known**, not unresolved.
+
+## UPDATE 1
+
+**HTTP:** 422 | **Stage:** `proposal_compatibility`
+
+### First Error
+
+```
+selectedQuestion is required when consequential unresolved unknowns remain after resolving the answered unknown
+```
+
+### Answer Meaning
+
+```json
+{
+  "userSupportedMeaning": "The user is unsure whether the projected office savings from the relocation are realistic.",
+  "possibleInference": "If projections are unrealistic, the financial justification for relocating may be flawed, potentially leading to increased or unchanged operating costs."
+}
+```
+
+### Support Category / Resolution Guidance
+
+**supportCategory populated:** NO (not present in answerMeaning)
+**resolutionGuidance populated:** NO (not present in answerMeaning)
+**Structured path:** NO — the structured field was not populated; meaning came through free-text `userSupportedMeaning` only.
+
+### Rejected Proposal Snapshot
+
+```json
+{
+  "answerMeaning": {
+    "userSupportedMeaning": "The user is unsure whether the projected office savings from the relocation are realistic.",
+    "possibleInference": "If projections are unrealistic, the financial justification for relocating may be flawed, potentially leading to increased or unchanged operating costs."
+  },
+  "updatedNodes": [],
+  "resolvedUnknownNodeIds": [],
+  "addedNodes": [
+    {
+      "id": "nsavings_reality",
+      "kind": "unknown",
+      "label": "Realism of projected office savings from relocation",
+      "description": "Whether anticipated cost reductions match achievable financial outcomes, needed to decide if the relocation meets its core objective.",
+      "parentId": null,
+      "dependsOn": ["n20in8o"],
+      "affects": [],
+      "childIds": []
+    }
+  ],
+  "addedEdges": [
+    {
+      "fromNodeId": "nsavings_reality",
+      "toNodeId": "n20in8o",
+      "relationship": "depends_on"
+    }
+  ]
+}
+```
+
+### Analysis of the Rejection
+
+The model attempted to create a dedicated savings-realism unknown node (`nsavings_reality`) — which is the correct semantic interpretation. However, it also set `updatedNodes: []` and `resolvedUnknownNodeIds: []`, meaning no existing nodes were updated or resolved. The proposal created a new consequential unresolved unknown without updating any existing node to reflect the uncertainty (e.g., downgrading `nx54wwa` from known to provisional as 57J.56 did).
+
+The system then rejected the proposal because creating a new consequential unknown requires a selected question for follow-up, but the proposal lacked this linkage. The rejection is structural: the model produced valid semantics but failed to complete the required graph mutation (updating existing nodes to reflect uncertainty) that would normally trigger the selected-question path.
+
+### Update 1 Classification: U1-FAIL
+
+No persistent savings-realism uncertainty was established in the graph because Update 1 was rejected. The proposed node (`nsavings_reality`) never entered the graph.
+
+## Reachable for Update 2?
+
+**NO.** Update 1 failed, so by experiment protocol the run stops. Update 2 is not reached.
+
+## Classification: D — UPDATE 1 FAILED
+
+The first turn never establishes the uncertainty needed for the inverse test. The model demonstrated correct semantic interpretation (it understood Answer 1 as savings-realism doubt and attempted to create a dedicated node), but failed at the structural linkage step: it did not update any existing node to reflect the uncertainty, leaving no selected-question trigger for downstream flow.
+
+## What This Establishes
+
+1. **Semantic interpretation works:** The model correctly interprets both Answer 1 and would have interpreted Answer 2 (had Update 1 succeeded) as savings-realism doubt.
+2. **Dedicated node creation intent is correct:** The model's attempt to create `nsavings_reality` confirms v0.21's prompt clarification successfully guides the model toward distinct unknown nodes rather than absorption.
+3. **Structural gap exposed:** The rejection reveals a gap where semantic interpretation succeeds but graph mutation fails silently — no existing node was updated (e.g., nx54wwa remained known instead of provisional), so the proposal lacked the structural trigger needed for question selection.
+
+## What This Does NOT Prove
+
+1. **Whether Answer 2 would have reused or duplicated:** We cannot answer the primary identity question because Update 1 never succeeded in establishing the persistent uncertainty that Update 2 would need to act upon.
+2. **Downstream investigation viability:** The graph was not updated, so downstream investigation cannot be tested.
+3. **Cross-domain generalisation:** Only tested on one scenario with one phrasing.
+4. **Whether the structural gap is specific to cold-start vs. mid-investigation:** This occurred at cold start where nx54wwa (known) needed updating alongside new node creation — a different mutation pattern than 57J.56's update path which DID update nx54wwa.
+
+## Production code changed: NO
+## Prompt changed during experiment: NO
+## Canonical harness restored: YES
+## Hardened no-retry behaviour preserved: YES
+## Ollama calls beyond harness count: 0
+## Dev server disturbed: NO