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ACP Internals

كيف يعمل ACP من الداخل

Developer8 minutes3 questions2026-08-09
The idea in one minute

Start with meaning, then move to detail.

This lesson explains ACP Internals as part of Hermes internals and extension points. You will learn what it does, when it matters, and the smallest safe test that proves it works.

If you are new

If you are new, do not memorize names. Focus on three questions: what problem does this solve, what access does it need, and how can you verify the result?

For hands-on use

For practice, inspect the first example, identify its effects, run it on test data, and compare the result with the source claim.

For specialists

For advanced readers, inspect Boot flow, Major components, HermesACPAgent, then verify failure modes and version compatibility.

What do you need first?

Know Python, Git, and basic project structure before changing code.

What will you know?

A clear outcome before you read.

  • Understand ACP Internals without assumed prior knowledge.
  • Separate the source description from what still needs testing in your environment.
  • Read the first command and identify its inputs and outputs before copying it.
Lesson terms

Short definitions before the details.

ACP
A protocol used to connect agent sessions and events to compatible clients and editors.
Session & memory
A session holds conversation context, while memory keeps selected facts that should persist.
Tool
A structured action the agent can call to read or change something.
Official page description

How the ACP adapter works: lifecycle, sessions, event bridge, approvals, and tool rendering

Topic map

What does the source say, and in what order?

  1. 01
    Boot flow

    Start here to understand the core idea or structure.

  2. 02
    Major components

    Read this after the foundation, then connect it to the previous step.

  3. 03
    HermesACPAgent

    Read this after the foundation, then connect it to the previous step.

  4. 04
    SessionManager

    Read this after the foundation, then connect it to the previous step.

  5. 05
    Event bridge

    Read this after the foundation, then connect it to the previous step.

  6. 06
    Permission bridge

    Read this after the foundation, then connect it to the previous step.

  7. 07
    Tool rendering helpers

    Read this after the foundation, then connect it to the previous step.

  8. 08
    Session lifecycle

    Read this after the foundation, then connect it to the previous step.

  9. 09
    Cancelation

    Read this after the foundation, then connect it to the previous step.

  10. 10
    Forking

    Finish here to verify the result and special cases.

Examples from the official page

Copy only after you understand the effect.

hermes acp / hermes-acp / python -m acp_adapter -> acp_adapter.entry.main() -> parse --version / --check / --setup before server startup -> load ~/.hermes/.env -> configure stderr logging -> construct HermesACPAgent -> acp.run_agent(agent, use_unstable_protocol=True)
### Permission bridge `acp_adapter/permissions.py` adapts dangerous terminal approval prompts into ACP permission requests. Mapping: - `allow_once` -> Hermes `once` - `allow_always` -> Hermes `always` - reject options -> Hermes `deny` Timeouts and bridge failures deny by default. ### Tool rendering helpers `acp_adapter/tools.py` maps Hermes tools to ACP tool kinds and builds editor-facing content. Examples: - `patch` / `write_file` -> file diffs - `terminal` -> shell command text - `read_file` / `search_files` -> text previews - large results -> truncated text blocks for UI safety ##
Try it now

Read the first command and identify its inputs and outputs before copying it.

Match every command to your installed Hermes version, review the files and accounts it can reach, and use non-sensitive data for the first test. If this explanation differs from the source, the official source wins.

Knowledge check

Three decisions before completion.

1. What is the source of truth when “ACP Internals” changes?
2. What is the best way to apply this lesson?
3. What should happen before a step can modify files or an external account?