feat: add codex agent adapter

[tumberger]

Summary

• Register Codex as a first-class agent adapter.
• Add Codex hook decoding/encoding for session, tool, prompt, and turn-stop events.

Review notes

• UserPromptSubmit is intentionally treated as a blocking event in the shared hook domain. In enforce mode, runtime/socket failures fail closed for UserPromptSubmit, matching Codex's ability to block prompts. Claude Guard user hooks still only install PreToolUse/PostToolUse, so this does not add a Claude user-hook install path.
• Codex Stop is treated as turn-scoped telemetry, not as a session-finalization event. Codex does not emit Claude's SessionEnd.

Verification

• go test ./...

[tumberger]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• feat: support codex permission requests #321
• feat: install codex self-serve hooks #320
• feat: add codex agent adapter #319 👈 (View in Graphite)
• refactor: introduce agent hook installer #318
• main

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[greptile-apps]

Greptile Summary

This PR adds Codex as a supported agent path. The main changes are:

• Codex agent registration in the CLI binary.
• Codex hook decoding for session, tool, lifecycle, and prompt events.
• Codex hook result encoding for allow, deny, updates, and context.
• Shared hook alias parsing for CLI hook event names.
• Prompt-submit routing through the synchronous enforcement path.

Confidence Score: 5/5

This looks safe to merge.

• No blocking issues found in the changed code.

Important Files Changed

Filename	Overview
internal/hookruntime/codex.go	Adds Codex event decoding, supported-event checks, input normalization, and result encoding.
internal/agent/codex/codex.go	Registers the Codex agent and wires it to the Codex hook runtime codec.
internal/hook/domain.go	Adds shared hook alias helpers and marks prompt-submit hooks as blockable.
internal/localruntime/service.go	Routes async ingestion based on normalized hook names and hook blockability.
cmd/kontext/main.go	Loads the Codex adapter and switches hook argument parsing to the shared alias parser.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
  A[Codex hook JSON] --> B[Codex adapter]
  B --> C[Decode Codex event]
  C --> D[Shared hook event]
  D --> E{Can this hook block?}
  E -->|PreToolUse or UserPromptSubmit| F[Evaluate synchronously]
  E -->|Other hooks| G[Ingest as telemetry]
  F --> H[Hook result]
  G --> H
  H --> I[Encode Codex result]
  I --> J[Codex response JSON]

Loading

%%{init: {'theme': 'base', 'themeVariables': {"darkMode": true, "background": "#0d1117", "primaryColor": "#21262d", "primaryTextColor": "#e6edf3", "primaryBorderColor": "#8b949e", "lineColor": "#8b949e", "textColor": "#e6edf3", "edgeLabelBackground": "#161b22", "actorBkg": "#21262d", "actorBorder": "#8b949e", "actorTextColor": "#e6edf3", "actorLineColor": "#8b949e", "signalColor": "#8b949e", "signalTextColor": "#e6edf3", "noteBkgColor": "#373320", "noteBorderColor": "#d4a72c", "noteTextColor": "#f0e6c0", "labelBoxBkgColor": "#21262d", "labelBoxBorderColor": "#8b949e", "labelTextColor": "#e6edf3", "loopTextColor": "#e6edf3", "activationBkgColor": "#30363d", "activationBorderColor": "#8b949e"}}}%%
flowchart TD
  A[Codex hook JSON] --> B[Codex adapter]
  B --> C[Decode Codex event]
  C --> D[Shared hook event]
  D --> E{Can this hook block?}
  E -->|PreToolUse or UserPromptSubmit| F[Evaluate synchronously]
  E -->|Other hooks| G[Ingest as telemetry]
  F --> H[Hook result]
  G --> H
  H --> I[Encode Codex result]
  I --> J[Codex response JSON]

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_{Reviews (2): Last reviewed commit: "feat: add codex agent adapter" | Re-trigger Greptile}

[tumberger]

@greptile check again

[hasandemirkiran]

A few notes on the adapter — the main one (the event set) ties into the codexmanaged side in #320. Details inline.