feat: deepen 268 exploitation skills; web session delete; CSS design system; JEV progress checkpoint

agents_md (skills):
- enrich all 255 vulns/ + 13 chains/ agents from thin one-liner stages to
  concrete playbooks: exact tools/commands, per-stack decision points, benign
  proof markers (unique OOB nonces, single reads, URLDNS-before-exec), explicit
  proof criteria, false-positive/pitfall sections, and chaining hooks. Every
  contract preserved (## User/System Prompt, {target}/{recon_json}, FINDING
  block, CWE/Severity, credits). avg 37->53 lines; loader parses all 449.

web console:
- delete a session/report: DELETE /api/runs/:id and DELETE /api/runs (all),
  a Delete button in the run detail and a hover ✕ per sidebar row (tested e2e)
- CSS design system: tokenise the loose values into one scale — 8-step type
  scale (was 10 ad-hoc sizes), radius/z-index/motion/scrim/terminal tokens,
  fix an undefined var(--muted); 66 tokens, 0 loose font sizes, all var() resolve
- stale version labels 4.0.0/4.2.0 -> 4.2.1

harness (JEV / System One):
- typesafe::progress_checkpoint (jev-skill agent-checkpoint pattern:
  continue/pivot/stop) wired into the attack-chain loop to stop looping rounds
  early; works with TypeSafe or local Laya via from_env(); honours --typesafe off
- 390 tests passing

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

agents_md/vulns/jwt_manipulation.md

@@ -3,8 +3,20 @@
 You are testing **{target}** for JWT Token Manipulation.
 **Recon Context:**
 {recon_json}
-**METHODOLOGY:**
-Decode JWT (header.payload.signature), test: algorithm none attack (change alg to none, remove signature), key confusion (RS256→HS256 using public key as HMAC secret), brute-force weak secrets (jwt_tool, hashcat), modify payload claims (role, user_id, exp), test expired token acceptance, kid injection.
+**METHODOLOGY — decode, attack the signature/claims, and PROVE server acceptance:**
+### 1. Capture and decode
+- Grab a real token (login via browser/API; check `Authorization`, cookies, `localStorage`).
+- Decode header+payload: `jwt_tool <JWT>` or `echo <part> | base64 -d`. Record `alg`, `kid`, and access-gating claims (`role`, `user_id`/`sub`, `email`, `exp`).
+### 2. Attack the signature (cheapest first)
+- `alg:none` — set `{"alg":"none"}`, strip signature: `jwt_tool <JWT> -X a`.
+- Key confusion RS256→HS256 — sign with the server's PUBLIC key bytes as the HMAC secret: `jwt_tool <JWT> -X k -pk public.pem`.
+- Weak HS256 secret — crack it: `jwt_tool <JWT> -C -d jwt.secrets.list` or `hashcat -m 16500 jwt.txt rockyou.txt`; re-sign once cracked.
+- `kid` injection — path traversal / SQLi to control the verification key.
+### 3. Attack the claims
+- Elevate `role`/`is_admin`, swap `user_id`/`sub`/`email` to another identity, extend/replay `exp` (test whether expired tokens are still accepted).
+### 4. Prove acceptance
+- Send the modified token to an authenticated endpoint; PROOF = the server returns the changed identity's / elevated data (200 with that content).
+- False positives: decoding a JWT is NOT a finding (anyone can); a 200 still reflecting your own identity (claim ignored); a 401 = control held; a public endpoint.
 ### Report
 ```
 FINDING:
@@ -12,10 +24,11 @@ FINDING:
 - Severity: High
 - CWE: CWE-347
 - Endpoint: [URL]
-- Payload: [exact payload/technique]
-- Evidence: [proof of exploitation]
-- Impact: [specific impact]
-- Remediation: [specific fix]
+- Payload: [exact payload/technique + signing command]
+- Evidence: [raw request with modified token + privileged/changed-identity response]
+- Impact: [specific impact — auth bypass / privilege escalation / account takeover]
+- Remediation: [specific fix — pin alg, strong secret, reject alg:none, verify exp/sig server-side]
 ```
+- Chaining hooks: forged tokens → admin API / IDOR at scale; a cracked HS secret → mint any token for the rest of the engagement.
 ## System Prompt
-You are a JWT Token Manipulation specialist. JWT manipulation requires showing the modified token is ACCEPTED by the server and grants different access. Decoding a JWT is NOT a finding — anyone can decode the payload.
+You are a JWT Token Manipulation specialist. JWT manipulation requires showing the modified token is ACCEPTED by the server and grants different/elevated access — quote the request and the changed-identity response. Decoding a JWT is NOT a finding; a 200 that still reflects your own identity, or a 401, is the control working, not a bypass. Try attacks cheapest-first (alg:none, key confusion, weak-secret crack, kid injection). Read-only; do not mint tokens for real users' accounts or change state. AUTHORIZED engagement.