install --target=hermes writes invalid YAML when platform_toolsets.cli already exists

[0Dy6h]

codegraph install --target=hermes writes invalid YAML when platform_toolsets already exists

Summary

When the target ~/.hermes/config.yaml already has a platform_toolsets.cli list using Hermes Agent's native indentation style (dash at the same column as the parent key, i.e. 2-space indent), codegraph install --target=hermes writes the new - mcp-codegraph entry with 4-space indentation. This breaks the list's structure and makes the file unparseable by PyYAML — Hermes Agent then fails to start.

Environment

• CodeGraph: 0.9.3 (npm @colbymchenry/codegraph)
• Hermes Agent: v0.14.0 (2026.5.16)
• OS: WSL2 (Ubuntu 24.04) on Windows 11, ext4
• Node: v22.22.2
• Python (for YAML check): 3.13

Minimal reproduction

Starting config (~/.hermes/config.yaml):

streaming:
  enabled: false
platform_toolsets:
  cli:
  - browser
  - clarify
  - terminal
mcp_servers:
  existing-server:
    command: echo
    args: [hello]
    enabled: true

Run:

codegraph install --target=hermes --yes

Resulting file:

streaming:
  enabled: false
platform_toolsets:
  cli:
    - mcp-codegraph       # ← 4-space indent (new entry)
  - browser                # ← 2-space indent (existing entries)
  - clarify
  - terminal
mcp_servers:
  existing-server:
    command: echo
    args: [hello]
    enabled: true

  codegraph:
    command: codegraph
    args:
      - serve
      - --mcp
    timeout: 120
    connect_timeout: 60
    enabled: true

YAML parser error:

yaml.parser.ParserError: while parsing a block mapping
  in "~/.hermes/config.yaml", line 4, column 3
expected <block end>, but found '-'
  in "~/.hermes/config.yaml", line 6, column 3

Root cause (apparent)

The installer is emitting list items under platform_toolsets.cli with 4-space indent ( - mcp-codegraph), but Hermes Agent's own config uses the indentation style where dashes sit at the parent key's column (2-space indent: - browser). Both are valid YAML in isolation, but mixing them inside the same list makes the parser think the 2-space dashes belong to a sibling of cli: rather than items of cli.

Suggested fix

Two options, either is fine:

1. Detect the existing list's dash column in platform_toolsets.cli and match it (most robust — handles users who use either style).
2. Use the same 2-space-dash style Hermes Agent uses by default. The Hermes config writer follows PyYAML default flow style, which is - item (no extra indent).

Side note: this platform_toolsets edit appears unnecessary

Hermes Agent's native MCP client doc (skill_view native-mcp) explicitly says:

After discovery, MCP tools are automatically injected into all hermes-* platform toolsets (CLI, Discord, Telegram, etc.). This means MCP tools are available in every conversation without any additional configuration.

So writing mcp_servers.codegraph alone is enough — the platform_toolsets.cli: [- mcp-codegraph] patch is redundant. If you remove that patch entirely, the bug disappears and the install becomes more minimal. Just adding mcp_servers.codegraph (which already gets its own indentation right) is the safer change.

Workaround for users hit by this

sed -i 's/^    - mcp-codegraph$/  - mcp-codegraph/' ~/.hermes/config.yaml
# verify:
python3 -c "import yaml; yaml.safe_load(open('$HOME/.hermes/config.yaml'))" && echo OK

Affected agent: Hermes only

Verified Claude Code, OpenCode, Cursor configs are all correctly written. The bug is specific to the Hermes Agent target.