ci: add strict case-contract test for examples/ctf-demo (P1-3)

- Refactor examples/ctf-demo to satisfy the review_case.py contract:
  split evidence/E-001-E-003.md into per-record E-001/E-002/E-003.md
  with ### E-xxx headings and severity/status/repro_command fields
- Add evidence/checksec-output.txt artifact with matching content_hash so
  --verify-hashes has a real object to verify
- Convert report.md finding/path sections to structured F-01/P-01 blocks
- New case-contract CI job runs review_case.py --verify-hashes --strict on
  examples/ctf-demo; local result: PASS (0 errors, 0 warnings)

.github/workflows/ci.yml

@@ -158,6 +158,15 @@ jobs:
         shell: pwsh
         run: ./skills/scripts/scan-leaks.ps1 -Path skills/field-journal
 
+  case-contract:
+    name: case contract test (ctf-demo)
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
+      - name: Review examples/ctf-demo under strict contract
+        shell: bash
+        run: python3 skills/case-review/scripts/review_case.py examples/ctf-demo --verify-hashes --strict
+
   version-check:
     name: version consistency
     runs-on: ubuntu-latest

examples/ctf-demo/evidence/E-001-E-003.md

@@ -1,42 +0,0 @@
-# Evidence E-001 — Binary triage
-
-- **id**: E-001
-- **date**: 2026-08-02T00:15:00
-- **title**: pwn1 ELF triage (checksec)
-- **finding**: ELF 64-bit x86-64, no PIE, NX enabled, partial RELRO, no canary on main
-- **repro_command**: `file ./pwn1 && checksec --file=./pwn1`
-- **output**:
-  ```text
-  ./pwn1: ELF 64-bit LSB executable, x86-64, dynamically linked
-  RELRO: Partial RELRO
-  Stack: No canary found
-  NX: NX enabled
-  PIE: PIE disabled
-  ```
-- **path**: Evidence → Finding → Path (skills/ops/evidence-finding-path.md)
-
----
-
-# Evidence E-002 — Overflow confirmation
-
-- **id**: E-002
-- **date**: 2026-08-02T00:40:00
-- **title**: gets() stack overflow in main
-- **finding**: main reads into buf[0x40] via gets(); return offset 0x48; no canary
-- **repro_command**: `python3 -c "print('A'*0x48 + 'B'*8)" | ./pwn1` (segfault at 0x4242424242424242)
-- **output**:
-  ```text
-  Program received signal SIGSEGV, Segmentation fault.
-  RIP=0x4242424242424242
-  ```
-
----
-
-# Evidence E-003 — Flag captured
-
-- **id**: E-003
-- **date**: 2026-08-02T01:10:00
-- **title**: remote exploit success
-- **finding**: ret2win payload works remotely, flag captured
-- **repro_command**: `python3 exploit.py REMOTE`
-- **output**: `ctf{example_flag_do_not_use}`

examples/ctf-demo/evidence/E-001.md

@@ -0,0 +1,19 @@
+### E-001
+
+- title: pwn1 ELF triage (checksec)
+- severity: info
+- status: observed
+- observed_at: 2026-08-02T00:15:00
+- source_type: command
+- source_ref: recon phase
+- repro_command: |
+    file ./pwn1 && checksec --file=./pwn1
+- raw_excerpt: |
+    ./pwn1: ELF 64-bit LSB executable, x86-64, dynamically linked
+    RELRO: Partial RELRO
+    Stack: No canary found
+    NX: NX enabled
+    PIE: PIE disabled
+- artifact_path: evidence/checksec-output.txt
+- content_hash: 395aa1546e0e22873e10334c4225097e9111f1b8fb5dcd1a2a3b7640d6fcc6ed
+- linked_workitem: WI-002

examples/ctf-demo/evidence/E-002.md

@@ -0,0 +1,15 @@
+### E-002
+
+- title: gets() stack overflow in main
+- severity: info
+- status: observed
+- observed_at: 2026-08-02T00:40:00
+- source_type: command
+- source_ref: static analysis
+- repro_command: |
+    python3 -c "print('A'*0x48 + 'B'*8)" | ./pwn1
+- raw_excerpt: |
+    Program received signal SIGSEGV, Segmentation fault.
+    RIP=0x4242424242424242
+- content_hash: n/a
+- linked_workitem: WI-003

examples/ctf-demo/evidence/E-003.md

@@ -0,0 +1,14 @@
+### E-003
+
+- title: remote exploit success
+- severity: high
+- status: validated
+- observed_at: 2026-08-02T01:10:00
+- source_type: command
+- source_ref: exploit phase
+- repro_command: |
+    python3 exploit.py REMOTE
+- raw_excerpt: |
+    ctf{{example_flag_do_not_use}}
+- content_hash: n/a
+- linked_workitem: WI-004

examples/ctf-demo/evidence/checksec-output.txt

@@ -0,0 +1,5 @@
+./pwn1: ELF 64-bit LSB executable, x86-64, dynamically linked
+RELRO: Partial RELRO
+Stack: No canary found
+NX: NX enabled
+PIE: PIE disabled

examples/ctf-demo/report/report.md

@@ -22,12 +22,35 @@ pwn1 为无 PIE/无 canary 的 64 位 ELF，main 使用 `gets()` 读取 0x40 缓
 
 ## 4. 发现
 
-| # | 严重度 | 描述 | 证据 |
+### F-01
-|---|--------|------|------|
+
-| F-01 | High (CTF) | gets() 栈溢出，ret 偏移 0x48，可 ROP/ret2win | E-001, E-002, E-003 |
+- title: gets() stack overflow in main (ret2win)
+- severity: high
+- status: validated
+- confidence: high
+- evidence_ids: [E-001, E-002, E-003]
+- location: pwn1:main — gets() into buf[0x40], return offset 0x48, no canary
+- impact: Remote code execution as the pwn1 process user; flag disclosure in CTF context.
+- repro_steps:
+  1. Triage the binary (E-001)
+  2. Confirm the overflow offset with a cyclic/crash test (E-002)
+  3. Send the ret2win payload against the remote service (E-003)
+- remediation: Replace gets() with fgets/read; enable canary, PIE and full RELRO; rely on ASLR.
 
 ## 5. 攻击路径（Evidence → Finding → Path）
 
+### P-01
+
+- title: pwn1 ret2win solve path
+- path_type: solve
+- start: challenge binary download
+- goal: flag capture
+- steps:
+  1. action: download and triage pwn1 — evidence: E-001 — finding: F-01 | none
+  2. action: decompile main and confirm gets() overflow — evidence: E-002 — finding: F-01
+  3. action: craft ret2win payload and verify remotely — evidence: E-003 — finding: F-01
+- residual_risks: none (isolated CTF lab)
+
 ```mermaid
 graph LR
   A[下载 pwn1] --> B[checksec 侦察]