agent-joule/dev-docs/ARCHITECTURE.md

Architecture & Integration

Generated 2026-06-14. How agent_mei_panel wires together internally, to the Joule host, and to its 16 external deps. file:line against audited HEAD.

Component map

   crates/zed/src/main.rs:770  agent_mei_panel::init(cx)
   crates/zed/src/zed.rs:704   AgentMeiPanel::load(...)  (initialize_panels)
            │
   init(cx) [agent_mei_panel.rs:84]                AgentMeiPanel (struct :177) owns:
    ├─ control::init_control_server(cx)              l0_cache: L0Cache               (joule-code-cascade)
    ├─ observe_new<Workspace> → ToggleFocus          l3_model: Option<Arc<L3Model>>  (jouleclaw-runtime/loader)
    └─ observe_new<Editor>   → LocalFimDelegate       cascade_gate: CascadeGate       (cascade_gate.rs / joule-code-jcp)
                                                      hooks: HookRegistry             (hooks.rs)
                                                      methodology: MethodologyTracker (methodology.rs)
                                                      session_mgr: SessionManager     (sessions.rs)
                                                      energy_counter: EnergyCounter   (jouleclaw-energy)

1. Cascade data flow

Entry submit_prompt (agent_mei_panel.rs:1600). Each tier guarded by authorize_tier(tier, intent); first to close wins.

submit_prompt :1600
 ├─ resolve_at_mentions → pending_context            :1608
 ├─ ensure_ledger_loaded / ensure_l2_loaded          :1618   (rehydrate L0/L2 across sessions)
 ├─ L0  authorize_tier(L0) → l0_cache.try_resolve     :1628   hit → note_close(L0,0) → RETURN :1646
 ├─ L1  attempt_l1_deterministic                      :1834   parse_substitution; buffer.set_text → record_tier_edit(L1)
 └─ attempt_l2_then_l3                                :1673
     ├─ L2  embed (GGUF as encoder) → cosine ≥ threshold → replay prior edit → record_tier_edit(L2)
     ├─ L3  attempt_l3_then_l4                         :1883
     │       energy_before; document_symbols (LSP) on fg :1927
     │       background: load_l3_model → codebase_index.search → format_symbol_context →
     │                   harness_prompt → l3_generate :1958
     │       FILE blocks → apply_multi_file_edit; else parse_edit;
     │       empty → send_to_l4; else review? stage_pending_edit : buffer.set_text + record_l3_edit
     └─ L4  send_to_l4                                 :2462
             authorize_tier(L4) DENY → "L4 denied by grant" RETURN  ← no-phone-home seam
             thread.send(ContentBlock) over ACP        :2491
             (close captured later via thread subscription — see §risks)

Edit review (stage_pending_edit:2178 → accept_pending_edit:2231 → apply_staged_now:2204): staging records a PendingEdit; buffers untouched until Accept (set_text + record_l3_edit). Reject just drops it. Control protocol exposes the same (accept/reject).

Energy (bracket_energy:2443): after − before from energy_uj_now; Estimator → measured_uj = None (honest). Counter from host_energy_counter:3850 — Apple IOReport (aarch64), NVML/RAPL (linux), else None.

Sealing (record_tier_edit:2542, the shared close path): bracket energy → build_coding_op → append_to_ledger:686 (hash-chained COSE_Sign1) → note_methodology_op → l0_cache.insert → record_review → note_close → index_for_l2 → attest_applied_edit:3039 (sandbox). Also folds the op into the active session via record_active_op:728.

L4 close is asymmetric: sealed not in send_to_l4 but in the thread subscription (:1123-1136) — on AcpThreadEvent, captured_op:3137 walks the thread's diffs into a CodingOp, then append_to_ledger + l0_cache.insert. (See risk #1.)

2. Joule integration seams

• Init: main.rs:770 agent_mei_panel::init(cx) (the zed.rs:5337 init is in mod test only — no production double-init).
• Panel load: zed.rs:704 AgentMeiPanel::load in initialize_panels, added via add_panel_when_ready alongside the other dock panels.
• Joule APIs touched: workspace::Workspace (panel host, actions, impl Panel); project::Project (agent_server_store, document_symbols LSP, open_buffer, worktrees); agent_servers/acp_thread/agent-client-protocol (ACP connection + L4 send + diff subscription); editor::Editor (prompt + FIM provider); language::Buffer/multi_buffer (edit application); lsp (symbol context); macOS sandbox (Seatbelt for the agent's run tool).

3. External dependency boundary (16 git deps, pinned 4132daa)

Dep	Used by	Purpose	Status
joule-code-cargo	panel, methodology	CodingOp, Edit, Anchor, SignedOp	Core
joule-code-cascade	panel, cascade_gate	L0Cache, Request, Stage	Core
joule-code-receipt	panel	Energy, Provenance, Receipt	Core
joule-code-schema	panel, gate, methodology, sessions	Tier, ContentId, ALG_ED25519	Core
joule-code-jcp	cascade_gate	JcpGate — tier auth + sealed receipts	Core (gate)
jcp-bridge	tool_gate	LocalToolGate — per-tool-call auth	Core (gate)
joule-code-identity	sessions, panel	Identity, ActorKind — did:key principals	Used
joule-code-spec	methodology	cite, coverage, Clause, SignedSpec	Used
joule-code-review	methodology, panel	two-stage review ledger	Used
joule-code-release	methodology	certify, ReleaseCertificate — ship door	Used (via ship_summary)
joule-code-joulecontract	methodology	frame_check — out-of-frame edit gate	Used
joulecontract-schema	methodology	Contract, Rigor	Thin (inert frame contract only)
jouleclaw-energy	panel	EnergyCounter + IOReport/NVML/RAPL	Core
jouleclaw-runtime	panel	generate, embed, cosine_similarity	Core (L3)
jouleclaw-loader-gguf	panel	GGUF reader/tokenizer + safetensors Mellum	Core (L3)
joule-code-conformance (dev)	tests	verify_pack over C1–C4 vectors	Test-only

Flags: joule-code-release's discharge gate is hardcoded false (ship_summary:2985) — ship door un-passable; jcp-bridge/ToolGate only active under JOULE_CODE_AGENT_TOOLS; Mellum surface only via JOULE_CODE_L3_ENGINE=mellum.

4. Subsystem wiring

• authorize_tier :2611 is the single junction composing hooks (PreTool, deny-wins, :2623) + cascade_gate (JCP grant + lifetime ceiling, :2629). Every tier passes through it.
• record_tier_edit :2542 is the close junction fanning into methodology, sessions, L0 cache, L2 index, reviews, sandbox attestation.
• control_dispatch :2261 is the headless seam — the control server (control.rs:185) and MCP bridge (run_mcp_bridge) drive the same panel methods a human action would.
• methodology ← note_methodology_op:943 signs+cites+frame-checks each op, exports to .joule/*.json. sessions ← ensure_session_mgr builds the manager with cascade_gate.grant(); worktrees back background sessions (active_session_worktree → agent cwd). tool_gate ← passed as the authorize_tool closure into local_agent::run_agent_loop.

5. Integration risks / danglers

1. L4 close depends on the thread subscription firing (:1123-1136). If the subscription is dropped on reconnect (:1141) or no diff event fires, the L4 turn produces no ledger op and no L0 entry — a silently lost close (unlike synchronous L0–L3). (See FINDINGS P1.)
2. Release/ship door structurally un-passable — contract_discharged = false hardcoded (:2985); the full release certificate can't be reached (only merge-via-verified can).
3. Session grant ↔ live gate is descriptor-only — SessionGrant is sealed into the open receipt but not bound to the live CascadeGate (sessions.rs:25-27); sessions with different declared grants are gated identically.
4. Heavy env-var gating — accountability is opt-in. Out of the box (no JOULE_CODE_GRANT/_LIFETIME_UJ/_AGENT_TOOLS/JOULECLAW_L3_MODEL/_REVIEW_EDITS/_CONTROL_SOCK) the cascade runs ungated and L4-reachable — no-phone-home is a configuration, not a default.
5. session_mgr silently absent outside a git repo — ensure_session_mgr returns early; record_active_op no-ops; closed ops hit the ledger but never fold into a session chain, with no surfaced warning.
6. joulecontract-schema near-vestigial — only builds an inert frame contract.
7. RAPL counter fragile by design — selected only if a read succeeds; normal Linux user → None → 0-J receipts that look honest but carry no measurement and no "unavailable" signal.
8. FIM provider attaches per-editor at observe_new time (set-once); editors opened before a model is configured stay no-op for the session.