[BUG] YAML field `target` is not honored

[kuisathaverat]

Describe the bug

If you set the target field in the configuration is not honored. The type of the field is string ot list in the documentation, but the reality is that it is a string of a comma-separated string

This configuration works

version: 0.1.0
description: test
author: foo
license: Apache-2.0
type: hybrid
target: copilot
compilation:
  strategy: single-file
  exclude:
  - docs/**
dependencies:
  apm: 
    - github/awesome-copilot
  mcp: []
scripts: {}

This configuration works too

version: 0.1.0
description: test
author: foo
license: Apache-2.0
type: hybrid
target: copilot,claude
compilation:
  strategy: single-file
  exclude:
  - docs/**
dependencies:
  apm: 
    - github/awesome-copilot
  mcp: []
scripts: {}

These two configurations fail with the same error

[x] [x] Unknown target '['copilot''

Valid targets: agent-skills, claude, codex, copilot, cursor, gemini, opencode, windsurf

Fix with one of:

  apm targets                            # see all supported harnesses
  apm install <pkg> --target agent-skills
  apm install <pkg> --dry-run

Or declare in apm.yml:

  targets:
    - agent-skills

version: 0.1.0
description: test
author: foo
license: Apache-2.0
type: hybrid
target: ['copilot', 'claude']
compilation:
  strategy: single-file
  exclude:
  - docs/**
dependencies:
  apm: 
    - github/awesome-copilot
  mcp: []
scripts: {}

version: 0.1.0
description: test
author: foo
license: Apache-2.0
type: hybrid
target: 
  - 'copilot'
  - 'claude'
compilation:
  strategy: single-file
  exclude:
  - docs/**
dependencies:
  apm: 
    - github/awesome-copilot
  mcp: []
scripts: {}

To Reproduce
Steps to reproduce the behavior:

1. Configure target field with claude and copilot in the apm.yml file
2. run target install
3. See error

Expected behavior

Only the selected target must be created without failures

Environment (please complete the following information):

• OS: macOS
• Python Version: 3.13.11
• APM Version: 0.12.3

Logs
If applicable, add any error logs or screenshots.

Additional context
Add any other context about the problem here.

[danielmeppiel]

Confirmed reproducible on v0.12.4 (current main).

Repro:

# apm.yml
name: test-1188
version: 0.1.0
type: hybrid
target:
  - 'copilot'
  - 'claude'
dependencies:
  apm:
    - github/awesome-copilot

$ apm install
[>] Resolving github/awesome-copilot...
[x] [x] Unknown target '['copilot''

Root cause: src/apm_cli/core/apm_yml.py::parse_targets_field (line 84-94, the singular-target: branch) only handles str and CSV. When a YAML list lands there, line 88 does str(raw) which produces the literal Python repr "['copilot', 'claude']", then comma-splitting produces ["['copilot'", "'claude']"], and the first token fails validation with the exact error you saw.

if has_target:
    raw = yaml_data["target"]
    ...
    raw_str = str(raw).strip()  # <-- list -> "['copilot', 'claude']"
    tokens = [t.strip() for t in raw_str.split(",") if t.strip()]
    _validate_canonical(tokens)  # <-- "['copilot'" fails

This is a duplicate parser; the sibling parse_target_field() in src/apm_cli/core/target_detection.py already handles list input correctly. The two parsers diverge -- and the install pipeline routes through the buggy one (install/phases/targets.py::_read_yaml_targets -> parse_targets_field).

Why --dry-run falsely passed: dry-run takes a different code path that goes through the working parse_target_field(). That's a second bug we should also fix (dry-run should exercise the same gate as real install).

Workarounds until the fix lands:

1. CSV form: target: copilot,claude
2. Or use the plural-list form: targets: [copilot, claude]

Both work today. The list-under-singular-target: form documented in the schema is the broken case.

Fix incoming.