Inside DeepSeek Harness
the everything-is-a-plugin agent runtime

flowchart TB
  subgraph BOOT["Boot Composition (Profiles × Bundles)"]
    P1["profile: web"] --> B1["bundle: dsh-base"]
    P1 --> B2["bundle: dsh-web-app"]
    P2["profile: headless"] --> B1
    P2 --> B3["bundle: dsh-headless"]
    B1 --> PATCH["cordis.patch.yml layers
(profile → home → --patch)"]
  end

  subgraph CTX["Shared Cordis Context (ctx.*)"]
    C1["ctx.sessions
append-only event log"]
    C2["ctx.systemPrompt
prompt section registry"]
    C3["ctx.tools
tool registry + guarded pipeline"]
    C4["ctx.agents
live agent registry"]
    C5["ctx.agentLoop
default driver (ReactLoop)"]
    C6["ctx.llm
adapter registry + stream waterfall"]
  end

  subgraph SEAMS["Swappable Capability Seams"]
    S1["ctx.fs → fs-local / fs-sandbox / fs-e2b"]
    S2["ctx.subprocess → local / e2b"]
    S3["ctx.shell → bash-local / bash-sandbox / pwsh"]
    S4["ctx.sessionPersistence → jsonl / sqlite"]
    S5["ctx.subagents → in-process / acp / codex / claude-code"]
    S6["ctx.web → exa / perplexity / deepseek search"]
  end

  BOOT --> CTX
  CTX --> SEAMS
  C5 --> C1 & C2 & C3 & C4 & C6
    

flowchart LR
  subgraph LOG["Append-Only SessionEvent Log (seq 1 → n)"]
    E1["turn/start"]
    E2["user/message"]
    E3["assistant/chunk × k"]
    E4["assistant/message"]
    E5["tool/call"]
    E6["tool/result"]
    E7["compaction/start"]
    E8["summary user/message (replace)"]
    E9["compaction/end"]
  end
  LOG --> FOLD["Surface Fold
replay + replace ops"]
  FOLD --> SURF["Surface Nodes
(3 eligible types)"]
  SURF --> DERIVE["deriveMessages()
projection rule"]
  DERIVE --> REQ["Model request messages"]
  SURF -. shadowed .-> OLD["shadowed range stays in log
for replay & audit"]
    

sequenceDiagram
  participant U as User
  participant A as Agent (ReactLoop)
  participant H as Hook listeners
  participant P as ctx.systemPrompt
  participant L as ctx.llm
  participant T as ctx.tools
  participant S as Session
  U->>A: followup(content)
  A->>S: turn/start
  Note over A: claim next-step input + one queued message
  A->>H: agent/pre-step (waterfall)
  H-->>A: enter(messages) | reject
  A->>S: step/start + user/message*
  A->>P: system-prompt/assemble (waterfall)
  A->>L: agent/request → llm/stream (waterfall)
  L-->>A: StreamChunk*
  A->>S: assistant/chunk* (durable)
  A->>S: assistant/message
  A->>T: classify calls → executeToolCalls
  T->>S: tool/call + tool/result (model order)
  A->>S: step/end
  Note over A: tools owe another request? → next step
  A->>H: agent/turn-stopping (serial checkpoint)
  A->>S: turn/end
    

flowchart TB
  subgraph SECTIONS["PromptSections (ordered, named)"]
    S1["order -100 · harness identity"]
    S2["order 0 · deployment persona
(PERSONA_ORDER)"]
    S3["order 100–199 · tool guidance"]
    S4["order n · plugin sections"]
  end
  subgraph OTHER["Other providers"]
    C1["PromptContexts
dynamic runtime snapshots"]
    T1["Tool schemas
from ctx.tools"]
    V1["Variables {{provider}} {{model}} {{cwd}}"]
  end
  SECTIONS --> ASSEMBLE["system-prompt/assemble
waterfall (scope-filtered)"]
  OTHER --> ASSEMBLE
  ASSEMBLE --> RENDER["renderPrompt()
interpolate → filter empty → join \\n\\n"]
  RENDER --> MODEL["model system prompt"]
  subgraph SCOPE["Scoped assembly"]
    SC1["global providers"]
    SC2["agent.ctx providers
(per-agent overrides)"]
  end
  SCOPE --> ASSEMBLE
    

flowchart TD
  M["assistant message has tool-call"]
  TC["session event: tool/call"]
  PRE["tools/pre-execute waterfall
hooks · permission · sandbox"]
  G["monotonic guards
deny or abstain"]
  APP["ctx.approval one-shot prompt
absent/unanswerable → deny"]
  EX["tools/execute waterfall
timeout · retry · metrics"]
  BODY["tool execute() body"]
  FSG["fs/write-intent · fs/edit-intent
tool-fs mutations only"]
  POST["tools/post-execute waterfall
accept · block · replace · add context"]
  NORM["registry normalization
snapshot failures → isError"]
  FIN["ToolDefinition.finalizeContent"]
  RES["tools/result
frozen authoritative outcome"]
  TR["session event: tool/result"]
  M --> TC --> PRE -->|allow| G
  PRE -->|ask| APP -->|allowed-once| G
  PRE -->|deny| DEN["denied — body skipped"]
  G -->|deny| DEN
  G -->|allow| EX --> BODY --> FSG
  FSG --> EX
  BODY --> POST --> NORM --> FIN --> RES --> TR
  PRE -. throw .-> NORM
  G -. throw .-> NORM
  EX -. wrapper throws .-> NORM
  POST -. throw .-> NORM
  DEN --> POST
    

flowchart TB
  P["post-step pressure event
or request-error (context overflow)"]
  M["token-meter replay fold
priced surface nodes"]
  SEL["selectCompactableRange()
retain priced recent tail"]
  PAIR["never split tool-call/result pair
toolPairingBalancedBefore"]
  START["session event: compaction/start
(the durable lock)"]
  SUM["summarize span → summary user/message"]
  STAB["stability check
whole-surface or selected-span"]
  CHG["SurfaceChangedError —
summary invalidated"]
  COMMIT["commit: replace surface span
shadow old nodes"]
  END["session event: compaction/end"]
  P --> M --> SEL --> PAIR --> START --> SUM --> STAB
  STAB -->|changed| CHG
  STAB -->|stable| COMMIT --> END