## What changed
- Preserve `encrypted_function_args` on function calls so an empty list can mark plaintext collaboration arguments across request replay.
- Deliver `spawn_agent`, `send_message`, and `followup_task` payloads as structured plaintext agent messages when that marker is present; retain encrypted delivery otherwise.
- Redact plaintext collaboration arguments from tool and communication logs, and omit the metadata when sending requests to non-OpenAI providers.
## Testing
- Cover serialization of empty encrypted-argument metadata and plaintext versus encrypted subagent message delivery.
- Verify plaintext tool arguments are redacted and provider-specific metadata is removed from non-OpenAI requests.
GitOrigin-RevId: 64db98ff0b61a3af2f04ed609292363f2e2362a8
## Why
Extensions that need to track runtime progress currently have no typed
host signal for tool execution. The goal extension in particular needs
to observe tool attempts without inspecting tool payloads, owning tool
implementations, or staying coupled to core-only runtime plumbing.
This adds a narrow lifecycle contributor API for host-owned tool
execution: extensions can observe when an accepted tool call starts and
how it finishes, while policy hooks and tool handlers continue to own
payload rewriting, blocking, and execution.
Relevant code:
-
[`ToolLifecycleContributor`](https://github.com/openai/codex/blob/3ad2850ffc7d8a1da19c65a92425637a59098f1b/codex-rs/ext/extension-api/src/contributors.rs#L119)
defines the extension-facing observer contract.
-
[`tool_lifecycle.rs`](https://github.com/openai/codex/blob/3ad2850ffc7d8a1da19c65a92425637a59098f1b/codex-rs/ext/extension-api/src/contributors/tool_lifecycle.rs)
defines the typed start/finish inputs, source, and outcome enums.
- [`notify_tool_start` /
`notify_tool_finish`](https://github.com/openai/codex/blob/3ad2850ffc7d8a1da19c65a92425637a59098f1b/codex-rs/core/src/tools/lifecycle.rs)
bridges core tool dispatch into the extension registry.
## What Changed
- Added `ToolLifecycleContributor` to `codex-extension-api`, including:
- `ToolStartInput`
- `ToolFinishInput`
- `ToolCallSource`
- `ToolCallOutcome`
- Added registration and lookup support on `ExtensionRegistryBuilder` /
`ExtensionRegistry`.
- Wired core tool dispatch to notify lifecycle contributors for:
- accepted tool starts
- completed tool calls, including the tool output success marker
- pre-tool-use blocks
- failures before or after the handler runs
- cancellation/abort in the parallel tool path
- Registered the goal extension as a lifecycle contributor and added the
outcome filter it will use for goal progress accounting.
## Test Coverage
- Added `dispatch_notifies_tool_lifecycle_contributors` to cover
lifecycle notification ordering and outcomes for successful and
handler-failed tool calls.
jif