From fd54549353228f78a7fa81063c6a821fd1732f09 Mon Sep 17 00:00:00 2001
From: Adrian Webb <adrian@webb.sh>
Date: Sun, 20 Sep 2026 15:29:50 -0400
Subject: [PATCH] fix: isolate simulation proposal revisions from workday
 discussion branch

---
 .../governance/proposal-version-content.ts    |  4 +++-
 .../proposal-workday-custody.test.ts          | 24 ++++++++++++++++++-
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/src/api/control-plane/governance/proposal-version-content.ts b/src/api/control-plane/governance/proposal-version-content.ts
index 77b305a8..b76db215 100644
--- a/src/api/control-plane/governance/proposal-version-content.ts
+++ b/src/api/control-plane/governance/proposal-version-content.ts
@@ -33,7 +33,9 @@ export async function commitProposalVersionContent(input: { store: any; proposal
 		throw Object.assign(new Error('Proposal authoring requires an active workday bound to this project and proposal.'), { status: 409, code: 'proposal_workday_scope_invalid' });
 	}
 	const simulation = run?.executionMode === 'simulation';
-	const simulationRef = simulation ? `refs/heads/${run.id}` : undefined;
+	// Keep proposal revisions on their exact source lineage. The workday's
+	// discussion branch can originate before this proposal existed.
+	const simulationRef = simulation ? `refs/heads/${run.id}-proposal-${createHash('sha256').update(text(input.proposal.id)).digest('hex').slice(0, 16)}` : undefined;
 	const sourceCommit = text(provenance.commitSha);
 	if (simulation && !/^[a-f0-9]{40}$/u.test(sourceCommit)) throw Object.assign(new Error('Simulation proposal authoring requires exact existing content provenance.'), { status: 409, code: 'proposal_simulation_source_required' });
 	const connection = await resolveKnowledgeGatewayConnection(input.store, { projectId, write: true, relationPaths: true, authoringPaths: true,
diff --git a/tests/unit/control-plane/governance/proposal-workday-custody.test.ts b/tests/unit/control-plane/governance/proposal-workday-custody.test.ts
index 8574af54..dd97d407 100644
--- a/tests/unit/control-plane/governance/proposal-workday-custody.test.ts
+++ b/tests/unit/control-plane/governance/proposal-workday-custody.test.ts
@@ -38,12 +38,34 @@ describe('workday-scoped proposal authoring', () => {
 	it('writes a simulation version from exact provenance to local workday custody without publication', async () => {
 		const { input, client, base, path } = fixture();
 		const result = await commitProposalVersionContent(input);
-		expect(client.createWorkspace).toHaveBeenCalledWith(expect.objectContaining({ baseRef: base, branchName: 'refs/heads/workday-1', allowedPaths: [path] }));
+		const proposalBranch = `refs/heads/workday-1-proposal-${createHash('sha256').update('proposal-1').digest('hex').slice(0, 16)}`;
+		expect(client.createWorkspace).toHaveBeenCalledWith(expect.objectContaining({ baseRef: base, branchName: proposalBranch, allowedPaths: [path] }));
 		expect(client.readRepositoryFiles).toHaveBeenCalledWith(expect.objectContaining({ ref: base }));
 		expect(result.update.contentProvenance).toMatchObject({ commitSha: 'b'.repeat(40), contentPath: path });
 		expect(recordTreeDxAuthoringState).not.toHaveBeenCalled(); expect(projectTreeDxCommitSignals).not.toHaveBeenCalled();
 		expect(client.closeWorkspace).toHaveBeenCalledExactlyOnceWith('workspace-1');
 	});
+	it('does not reuse an advanced discussion branch that lacks the proposal source', async () => {
+		const { input, client, base } = fixture();
+		client.createWorkspace.mockImplementationOnce(async request => {
+			if (request.branchName === 'refs/heads/workday-1' && request.baseRef === base) {
+				throw new Error('Workspace branch already exists at a different commit.');
+			}
+			return { workspaceId: 'workspace-1', baseCommitSha: base };
+		});
+		await expect(commitProposalVersionContent(input)).resolves.toMatchObject({ update: { contentProvenance: { commitSha: 'b'.repeat(40) } } });
+		expect(client.createWorkspace.mock.calls[0]?.[0].branchName).not.toBe('refs/heads/workday-1');
+	});
+	it('starts a later estimate version from its exact prior proposal commit on the same simulation branch', async () => {
+		const { input, client } = fixture();
+		input.proposal.metadata.contentProvenance.commitSha = 'b'.repeat(40);
+		const first = await commitProposalVersionContent(input);
+		const second = await commitProposalVersionContent(input);
+		expect(client.createWorkspace).toHaveBeenCalledTimes(2);
+		expect(client.createWorkspace.mock.calls[0]?.[0].branchName).toBe(client.createWorkspace.mock.calls[1]?.[0].branchName);
+		expect(client.createWorkspace.mock.calls[1]?.[0].baseRef).toBe('b'.repeat(40));
+		expect(first.update.contentProvenance.commitSha).toBe(second.update.contentProvenance.commitSha);
+	});
 	it.each(['missing', 'terminal', 'project', 'proposal', 'expired'])('rejects %s workday scope before issuing a workspace', async invalid => {
 		const { run, input, client } = fixture();
 		if (invalid === 'missing') vi.mocked(CapacityWorkdayRunRepository.prototype.get).mockResolvedValue(null);