diff --git a/src/domain/policy.test.ts b/src/domain/policy.test.ts
index 224f29e..9b532eb 100644
--- a/src/domain/policy.test.ts
+++ b/src/domain/policy.test.ts
@@ -8,6 +8,12 @@ const policy: AgentPolicy = {
   requireIntentNote: true,
 }
 
+const validDraft = {
+  amountSol: 0.025,
+  intentNote: 'Pay devnet test invoice',
+  recipient: 'Recipient111',
+}
+
 describe('evaluateAction', () => {
   it('allows an action that satisfies every local safeguard', () => {
     const result = evaluateAction(
@@ -19,28 +25,149 @@ describe('evaluateAction', () => {
     expect(result.decision).toBe('ALLOW')
   })
 
-  it('blocks a recipient that was not locally approved', () => {
+  // ── Boundary: invalid amounts ──────────────────────────────────────
+
+  it('blocks a NaN transfer amount', () => {
     const result = evaluateAction(
-      { amountSol: 0.025, intentNote: 'Pay devnet test invoice', recipient: 'Unknown111' },
+      { ...validDraft, amountSol: NaN },
       policy,
       0,
     )
 
     expect(result.decision).toBe('BLOCK')
-    expect(result.reason).toBe('Recipient allowlist')
   })
 
-  it('blocks a transfer that would exceed the remaining daily budget', () => {
+  it('blocks a zero transfer amount', () => {
     const result = evaluateAction(
-      { amountSol: 0.025, intentNote: 'Pay devnet test invoice', recipient: 'Recipient111' },
+      { ...validDraft, amountSol: 0 },
+      policy,
+      0,
+    )
+
+    expect(result.decision).toBe('BLOCK')
+  })
+
+  it('blocks a negative transfer amount', () => {
+    const result = evaluateAction(
+      { ...validDraft, amountSol: -1 },
+      policy,
+      0,
+    )
+
+    expect(result.decision).toBe('BLOCK')
+  })
+
+  // ── Boundary: per-action cap ───────────────────────────────────────
+
+  it('blocks an amount above the per-action cap', () => {
+    const result = evaluateAction(
+      { ...validDraft, amountSol: 0.051 },
+      policy,
+      0,
+    )
+
+    expect(result.decision).toBe('BLOCK')
+    expect(result.reason).toBe('Per-action budget')
+  })
+
+  it('allows an amount exactly equal to the per-action cap', () => {
+    const result = evaluateAction(
+      { ...validDraft, amountSol: 0.05 },
+      policy,
+      0,
+    )
+
+    expect(result.decision).toBe('ALLOW')
+  })
+
+  // ── Boundary: daily cap ────────────────────────────────────────────
+
+  it('allows a transfer that exactly reaches the daily cap', () => {
+    // spentTodaySol=0.15 + amountSol=0.05 = dailyLimitSol=0.2
+    const result = evaluateAction(
+      { ...validDraft, amountSol: 0.05 },
+      policy,
+      0.15,
+    )
+
+    expect(result.decision).toBe('ALLOW')
+  })
+
+  it('blocks a transfer exceeding the daily cap by the smallest practical value', () => {
+    // spentTodaySol=0.18 + amountSol=0.03 = 0.21 > dailyLimitSol=0.2
+    // amountSol=0.03 is within per-action cap (0.05), so daily budget check is reached
+    const result = evaluateAction(
+      { ...validDraft, amountSol: 0.03 },
       policy,
-      0.19,
+      0.18,
     )
 
     expect(result.decision).toBe('BLOCK')
     expect(result.reason).toBe('Daily budget')
   })
 
+  // ── Boundary: intent note length ───────────────────────────────────
+
+  it('blocks a required intent note shorter than 12 trimmed characters', () => {
+    const result = evaluateAction(
+      { ...validDraft, intentNote: 'Short' },
+      policy,
+      0,
+    )
+
+    expect(result.decision).toBe('BLOCK')
+    expect(result.reason).toBe('Intent evidence')
+  })
+
+  it('allows an intent note exactly 12 trimmed characters', () => {
+    const result = evaluateAction(
+      { ...validDraft, intentNote: 'Twelve chars' },  // exactly 12 chars
+      policy,
+      0,
+    )
+
+    expect(result.decision).toBe('ALLOW')
+  })
+
+  // ── Boundary: whitespace handling ──────────────────────────────────
+
+  it('does not let leading/trailing whitespace bypass the recipient allowlist', () => {
+    // Recipient is trimmed, so '  Recipient111  ' should match the allowlist
+    const result = evaluateAction(
+      { ...validDraft, recipient: '  Recipient111  ' },
+      policy,
+      0,
+    )
+
+    expect(result.decision).toBe('ALLOW')
+  })
+
+  it('does not let leading/trailing whitespace bypass the intent note length check', () => {
+    // '  Short  ' trimmed === 'Short' (5 chars < 12)
+    const result = evaluateAction(
+      { ...validDraft, intentNote: '  Short  ' },
+      policy,
+      0,
+    )
+
+    expect(result.decision).toBe('BLOCK')
+    expect(result.reason).toBe('Intent evidence')
+  })
+
+  it('blocks an unknown recipient even with whitespace around it', () => {
+    // '  Unknown111  ' trimmed === 'Unknown111' not in allowlist
+    const result = evaluateAction(
+      { ...validDraft, recipient: '  Unknown111  ' },
+      policy,
+      0,
+    )
+
+    expect(result.decision).toBe('BLOCK')
+    expect(result.reason).toBe('Recipient allowlist')
+  })
+
+  // ── Existing: fingerprint binding ──────────────────────────────────
+
   it('binds an approval to the recipient, amount, and declared intent', () => {
     const approved = actionFingerprint({
       amountSol: 0.025,
@@ -64,4 +191,4 @@ describe('evaluateAction', () => {
       recipient: 'Recipient222',
     })).not.toBe(approved)
   })
-})
+})
\ No newline at end of file
diff --git a/src/domain/receipt.test.ts b/src/domain/receipt.test.ts
index 12b453e..8e46a2f 100644
--- a/src/domain/receipt.test.ts
+++ b/src/domain/receipt.test.ts
@@ -1,5 +1,5 @@
 import { describe, expect, it } from 'vitest'
-import { createReceipt, shortHash } from './receipt'
+import { createReceipt, shortHash, verifyReceiptChain } from './receipt'
 
 const action = {
   amountSol: 0.025,
@@ -31,4 +31,113 @@ describe('audit receipts', () => {
     expect(second.hash).not.toBe(first.hash)
     expect(shortHash(first.hash)).toMatch(/^[a-f0-9]{8}\.\.\.[a-f0-9]{6}$/)
   })
+
+  it('verifyReceiptChain validates a valid chain', async () => {
+    const first = await createReceipt({
+      action,
+      agentId: 'audit-agent.local',
+      decision: 'BLOCK',
+      previousHash: null,
+      reason: 'Recipient allowlist',
+      status: 'blocked',
+    })
+    const second = await createReceipt({
+      action,
+      agentId: 'audit-agent.local',
+      decision: 'ALLOW',
+      previousHash: first.hash,
+      reason: 'All local safeguards passed.',
+      status: 'approved',
+    })
+    const third = await createReceipt({
+      action,
+      agentId: 'audit-agent.local',
+      decision: 'ALLOW',
+      previousHash: second.hash,
+      reason: 'Submitted to chain.',
+      status: 'submitted',
+    })
+
+    const result = await verifyReceiptChain([first, second, third])
+    expect(result.valid).toBe(true)
+    expect(result.errors).toEqual([])
+  })
+
+  it('verifyReceiptChain rejects chain with invalid first receipt previousHash', async () => {
+    const receipt = await createReceipt({
+      action,
+      agentId: 'audit-agent.local',
+      decision: 'ALLOW',
+      previousHash: null,
+      reason: 'Test',
+      status: 'approved',
+    })
+    const tampered = { ...receipt, previousHash: 'fake-hash' }
+
+    const result = await verifyReceiptChain([tampered])
+    expect(result.valid).toBe(false)
+    expect(result.errors.length).toBeGreaterThanOrEqual(1)
+    expect(result.errors[0]).toContain('previousHash')
+  })
+
+  it('verifyReceiptChain rejects chain with broken hash linkage', async () => {
+    const first = await createReceipt({
+      action,
+      agentId: 'audit-agent.local',
+      decision: 'ALLOW',
+      previousHash: null,
+      reason: 'First',
+      status: 'approved',
+    })
+    const second = await createReceipt({
+      action,
+      agentId: 'audit-agent.local',
+      decision: 'ALLOW',
+      previousHash: first.hash,
+      reason: 'Second',
+      status: 'approved',
+    })
+    const tampered = { ...second, previousHash: 'wrong-hash' }
+
+    const result = await verifyReceiptChain([first, tampered])
+    expect(result.valid).toBe(false)
+    expect(result.errors.some((e) => e.includes('previousHash'))).toBe(true)
+  })
+
+  it('verifyReceiptChain rejects chain with tampered content', async () => {
+    const first = await createReceipt({
+      action,
+      agentId: 'audit-agent.local',
+      decision: 'ALLOW',
+      previousHash: null,
+      reason: 'Original reason',
+      status: 'approved',
+    })
+    const tampered = { ...first, reason: 'Tampered reason' }
+
+    const result = await verifyReceiptChain([tampered])
+    expect(result.valid).toBe(false)
+    expect(result.errors.some((e) => e.includes('hash mismatch'))).toBe(true)
+  })
+
+  it('verifyReceiptChain returns valid for empty chain', async () => {
+    const result = await verifyReceiptChain([])
+    expect(result.valid).toBe(true)
+    expect(result.errors).toEqual([])
+  })
+
+  it('verifyReceiptChain returns valid for single receipt', async () => {
+    const receipt = await createReceipt({
+      action,
+      agentId: 'audit-agent.local',
+      decision: 'ALLOW',
+      previousHash: null,
+      reason: 'Single receipt',
+      status: 'approved',
+    })
+
+    const result = await verifyReceiptChain([receipt])
+    expect(result.valid).toBe(true)
+    expect(result.errors).toEqual([])
+  })
 })
diff --git a/src/domain/receipt.ts b/src/domain/receipt.ts
index e0a8484..b93d3e8 100644
--- a/src/domain/receipt.ts
+++ b/src/domain/receipt.ts
@@ -36,3 +36,41 @@ export function shortHash(hash: string | null | undefined): string {
   if (!hash) return 'Genesis'
   return `${hash.slice(0, 8)}...${hash.slice(-6)}`
 }
+
+export type VerificationResult = {
+  valid: boolean
+  errors: string[]
+}
+
+export async function verifyReceiptChain(receipts: AuditReceipt[]): Promise<VerificationResult> {
+  const errors: string[] = []
+
+  if (receipts.length === 0) {
+    return { valid: true, errors: [] }
+  }
+
+  if (receipts[0].previousHash !== null) {
+    errors.push(`First receipt's previousHash is "${receipts[0].previousHash}", expected null`)
+  }
+
+  for (let i = 0; i < receipts.length; i++) {
+    const receipt = receipts[i]
+
+    const { hash: _storedHash, transactionSignature: _txSig, ...fields } = receipt
+    const payload = JSON.stringify(fields)
+    const expectedHash = await sha256(payload)
+
+    if (expectedHash !== receipt.hash) {
+      errors.push(`Receipt ${i} hash mismatch: expected "${expectedHash}", got "${receipt.hash}"`)
+    }
+
+    if (i > 0) {
+      const prev = receipts[i - 1]
+      if (receipt.previousHash !== prev.hash) {
+        errors.push(`Receipt ${i} previousHash "${receipt.previousHash}" does not match receipt ${i - 1} hash "${prev.hash}"`)
+      }
+    }
+  }
+
+  return { valid: errors.length === 0, errors }
+}