Add tool lifecycle extension contributor

[jif-oai]

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 defines the extension-facing observer contract.
• tool_lifecycle.rs defines the typed start/finish inputs, source, and outcome enums.
• notify_tool_start / notify_tool_finish 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-oai]

@codex review

[chatgpt-codex-connector]

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[jif-oai]

@codex review

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: d0c284ab43

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".