Reporter Notes

Notes

Candidate Arcs

1. Hidden turn context becomes queued thread settings.

2. Pending input and subagent mailbox delivery get one owner.

3. Subagent startup becomes a lifecycle event with injected context.

4. Gemini CLI adds a feature flag for session-based subagent invocation.

5. Terminal output classification becomes PTY-aware rather than byte-naive.

Interpretation

The shared pattern is not "more tools." It is runtime state becoming explicit enough to be ordered, observed, tested, and surfaced. The strongest Codex evidence is internal but concrete: new operation names, events, queue ownership, and hook schemas. The Gemini evidence is narrower but useful because it shows the same concern at two boundaries: subagent invocation path and shell stream classification.

Claims Kept Conservative

• Codex is moving away from OverrideTurnContext toward queued ThreadSettings; this is directly stated in the commit message and diff.
• Codex consolidated pending input, next-turn queued response items, and mailbox delivery behind InputQueue; this is directly stated in the commit message and visible in the diff.
• Gemini added an experimental flag for AgentSession-backed subagent invocations; this is directly stated in PR #26947 and docs.
• Gemini's Windows PTY fix strips ANSI control sequences and uses a PTY-aware binary check; this is visible in commit f09d45d.

Claims Avoided

• No claim that these changes are shipped in a stable release.
• No claim that Gemini's subagent session flag is enabled by default; the docs say default false.
• No claim that Codex has completed the full seven-PR thread settings stack; the article only cites observed merged commits and public commit metadata.

Primary Evidence

• OpenAI Codex commit a668379abf0f67d81a61dc971ea463c483846fd2, [5 of 7] Replace OverrideTurnContext with ThreadSettings (#22508): https://github.com/openai/codex/commit/a668379abf0f67d81a61dc971ea463c483846fd2
• Evidence used: Op::ThreadSettings, ThreadSettingsApplied, settings-only updates routed through the submission queue, and deletion of Op::OverrideTurnContext.
• OpenAI Codex commit afa0101ae222792c1c7e072107e1eb7b72c19b7b, [codex] Move pending input into input queue (#22728): https://github.com/openai/codex/commit/afa0101ae222792c1c7e072107e1eb7b72c19b7b
• Evidence used: new session/input_queue.rs, queue ownership for pending input, next-turn queued items, and mailbox delivery coordination.
• OpenAI Codex commit d661ab70eda6bde758d7e48d6bf3638523cb014c, Add SubagentStart hook (#22782): https://github.com/openai/codex/commit/d661ab70eda6bde758d7e48d6bf3638523cb014c
• Evidence used: SubagentStart runs for thread-spawned subagents before first model request, includes agent_id and agent_type, and can add context to the child conversation.
• OpenAI Codex commit 05b8ce43541bbcd3ed14a21ea3f103c20cb9392b, chore: namespace v1 sub-agent tools (#23475): https://github.com/openai/codex/commit/05b8ce43541bbcd3ed14a21ea3f103c20cb9392b
• Evidence used: spawn_agent, send_input, resume_agent, wait_agent, and close_agent moved under the multi_agent_v1 namespace.
• Google Gemini CLI PR #26947, feat(core): add adk.agentSessionSubagentEnabled flag: https://github.com/google-gemini/gemini-cli/pull/26947
• Evidence used: merged PR body, changed files, 43 additions, and configuration docs describing experimental.adk.agentSessionSubagentEnabled.
• Google Gemini CLI patch in packages/core/src/config/config.ts from PR #26947.
• Evidence used: agentSessionSubagentEnabled?: boolean, class field initialization, and isAgentSessionSubagentEnabled() getter.
• Google Gemini CLI patch in docs/reference/configuration.md from PR #26947.
• Evidence used: docs state the flag routes subagent invocations through the AgentSession protocol instead of legacy executors.
• Google Gemini CLI commit f09d45d13338b385caf6bf49ec74900caa4c24b0, fix(core): prevent isBinary false-positive on Windows PTY streams (#26565): https://github.com/google-gemini/gemini-cli/commit/f09d45d13338b385caf6bf49ec74900caa4c24b0
• Evidence used: ShellExecutionService now calls isBinary(sniffBuffer, 512, true), stripAnsiFromBuffer was added, and tests cover Windows PTY output with ANSI sequences and null bytes.
• Gemini CLI subagents documentation: https://github.com/google-gemini/gemini-cli/blob/main/docs/core/subagents.md
• Evidence used: subagents have separate context windows and can be enabled or disabled through settings.

Evidence Limits

• The article does not claim that Codex and Gemini share an implementation or standard. It claims convergent pressure around explicit runtime state.
• The article does not claim that all cited changes are available in stable end-user releases.
• Gemini's AgentSession subagent flag is default-off, so the article frames it as rollout plumbing rather than current default behavior.