Codex prompts generated by OpenSpec do not inject arguments ($ARGUMENTS missing)

[zxfxpower]

Summary:
OpenSpec generates Codex prompts in ~/.codex/prompts/opsx-*.md without $ARGUMENTS (or $1..$9) placeholders. As a result, when invoking /prompts:opsx-ff <description> in Codex, the input is not visible to the prompt, and the skill
asks the user to describe the change again.

Steps to reproduce:

1. Install OpenSpec v1.1.1 and run openspec init --tools codex or openspec update.
2. Check ~/.codex/prompts/opsx-ff.md — note there is no $ARGUMENTS in the body.
3. In Codex, run: /prompts:opsx-ff add a new action "partitioned storage" on the device list page
4. The prompt asks “Please describe what change you want to build or fix,” ignoring the provided argument.

Expected:
Prompt should receive and use the arguments (via $ARGUMENTS or $1..$9), so it does not ask for the change again.

Actual:
Arguments are not injected; prompt behaves as if no input was provided.

Environment:

• OpenSpec: v1.1.1
• Codex CLI: v0.93.0
• OS: macOS (Apple Silicon)

Additional context:

• In pre‑1.0 versions, the Codex prompt openspec-proposal.md already included $ARGUMENTS, so arguments were injected correctly. This suggests a regression after the migration to opsx prompts.

Suggested fix:
Add $ARGUMENTS (or $1..$9) to the Codex prompt template, e.g. in src/core/command-generation/adapters/codex.ts or in the opsx prompt bodies, so arguments are passed through. Codex docs confirm $ARGUMENTS is supported.

[zxfxpower]

Additional analysis (regression evidence):

In pre‑1.0 versions (e.g. v0.23.0), the Codex slash command generator explicitly injected $ARGUMENTS in the prompt frontmatter/body.

Reference:

• v0.23.0: src/core/configurators/slash/codex.ts
  • getFrontmatter() returns YAML frontmatter followed by $ARGUMENTS for proposal/apply/archive
  • This was required for Codex argument injection and was covered by tests

In v1.0+ (current v1.1.1), the new Codex adapter in src/core/command-generation/adapters/codex.ts only emits frontmatter + body, but does not include $ARGUMENTS. As a result, arguments passed in /prompts:opsx-ff <...> are
not visible to the prompt and it asks for input again.

This appears to be a regression introduced during the migration from legacy slash commands to the new skills/command-generation system.

[zxfxpower]

Additional issue (Codex command hints):

In Codex prompt files (opsx-*.md), the instructions and examples often reference /opsx:apply, /opsx:ff, etc.
However, in Codex the correct invocation format is /prompts:opsx-apply, /prompts:opsx-ff, etc.

This mismatch is confusing and leads to failed command invocation in Codex.

Suggested fix:

• Update Codex prompt templates to use /prompts:opsx-* in all examples and hints (or render command references via a tool-aware formatter).

[zxfxpower]

Requesting triage / priority:
This blocks Codex users from using opsx-ff/opsx-apply with arguments (input ignored).
Fix seems small: inject $ARGUMENTS (or $1..$9) into Codex prompt templates (adapters/codex.ts).
Happy to test a patch if you have a branch.

[zxfxpower]

Likely not intentional. During the 1.0 migration, the new Codex adapter was introduced without $ARGUMENTS support (#556), and the legacy configurator that did include $ARGUMENTS was later removed in #565. There’s no explicit design note in #565 saying “drop arguments,” and the specs still mention $ARGUMENTS, so this looks like a regression from the migration rather than a deliberate change.