## Why
Experimental context activation previously checked the provider and account eligibility without checking model support. Child sessions also inherited token-budget activation from their parent, even when starting fresh with a different model.
## What changed
- Add `ModelInfo.supports_experimental_context`, defaulting to `false`, and enable it for the bundled `gpt-6-astra` model. Require this capability when activating experimental context.
- Snapshot configured token-budget preferences before startup activation. Restore them for fresh child sessions before applying their starting model's defaults, while history forks retain their parent's activation.
- Pass unresolved token-budget preferences to child sessions so they can use their own model's prompts.
## Testing
Extend coverage for unsupported models, model-switch guidance under explicit and experimental activation, and child configuration from both active and inactive parents. Verify that omitted capability metadata defaults to `false`.
GitOrigin-RevId: 02df9e171682267232fa923d5ea3f7af36527808
## What changed
- Add the under-development `features.context_management.experimental_mode` configuration and schema.
- For eligible ChatGPT Plus, Pro, and Pro Lite sessions using the Codex backend, enable token-budget context, history notes, and the `new_context` tool when experimental context management is configured.
- Keep the feature disabled for custom providers, provider credentials, non-Codex endpoints, and temporary structured threads.
## Testing
- Cover subscription eligibility, backend restrictions, configuration resolution, token-budget guidance, and temporary-thread overrides.
GitOrigin-RevId: 19402af19c4d69e09a7cdb3687ee7d233f6a562a
## What changed
- Emit a `codex_thread_hint_status` analytics event for each native history-notes thread hint attempt.
- Report whether retrieval was successful or failed along with thread context and timing, without including hint contents.
- Treat valid empty responses as successful retrievals while continuing to omit them from the context window.
## Testing
- Extend the app-server history-notes tests to verify success, empty-result success, and backend failure statuses.
GitOrigin-RevId: b9462f312847e8c871ed2be0c8cf8df0928a7fdd
## What changed
- Add model metadata flags for enabling token budgeting and its history-notes extension.
- Apply those activation defaults once at thread startup when the user has not explicitly configured token budgeting, while respecting managed feature requirements.
- Continue resolving model-owned prompts for the active model so model switches can use their own token-budget guidance.
## Testing
- Update the token-budget integration test to verify that model metadata activates the feature without manual configuration.
GitOrigin-RevId: 73a32623eaeabb9243e240c43da7a5e7e93e9a19
## What changed
- Set `history_ingest_requested` to `true` in Responses turn metadata when the
history-notes token-budget extension is enabled.
- Reserve the metadata key so caller-provided metadata cannot override the
core-owned value, and omit it when the extension is disabled.
GitOrigin-RevId: e750bcb729292c407e1d443857cdb584a88aac97
## Why
History and notes results are already limited by the backend using the requested
output budget before encryption. Applying another client-side limit can reject
or truncate an already bounded response.
## What changed
- Return encrypted history and notes results without an additional size check.
- Preserve fallback JSON results instead of truncating them again when building
the tool response.
GitOrigin-RevId: 97e7a59a13e8d485cc3c613d0fdf8073f6eb67ab
## What changed
Return consistent `Unable to perform operation:` messages for provider,
authentication, request construction, transport, and response parsing failures.
Do not include the underlying error details in these user-facing messages.
GitOrigin-RevId: c23fe7713f9d61e5f013ef217e1c0bdc2b824d83
## What changed
- Serialize each history and notes request's output truncation policy into the
`x-openai-tool-output-truncation-policy` header.
- Forward the invoking tool call's policy for tool requests and use the thread
hint byte limit for context-contributor requests.
GitOrigin-RevId: 9d4e61480397b325efdb033861893e88c708de3b
## What changed
- Mark history and notes search queries, appended note text, and replacement note text as encrypted in their tool schemas.
- Send `x-openai-encrypted-tool-arguments: true` for the corresponding backend routes without changing the JSON request body.
## Testing
- Cover encrypted schema fields and backend headers for history search, notes search, append, and write calls.
- Verify unrelated history and notes requests do not receive the encrypted-arguments header.
GitOrigin-RevId: 58263cff832c979b436ddb4013b5c27218aca678
## What changed
- Register the history-notes extension as a context contributor and fetch `thread_hint` from the configured history-notes backend.
- Add non-empty hints of at most 4,000 bytes to the context-window prompt, and omit hints when the request fails or the response is missing, empty, or oversized.
- Verify that app-server sessions use the native backend when `use_history_notes_extension` is enabled and retain the MCP bridge behavior when it is disabled.
## Testing
- Cover hint injection, request context, response validation, backend failures, and disabled-extension behavior in history-notes and app-server tests.
GitOrigin-RevId: 344a7bb79d962ea8b7c969f25b67a79423fc7fcc
## What changed
- Add a `ContextWindow` prompt slot for thread-scoped extension contributions.
- Include fragments in that slot in the token-budget context-window message.
- Keep the MCP `notes/thread_hint` bridge when the native history-notes extension is disabled, without falling back to it after a native request failure.
GitOrigin-RevId: befcb7cc8570b846094b2b542a112b186b39a30a
## What changed
Rename the token-budget configuration key and its Rust field from
`use_history_notes_history` to `use_history_notes_extension`. Update the config
schema, extension gating, explicit-setting detection, and tests to use the new
name consistently.
GitOrigin-RevId: b6a514e23f02095fcd1d35dc42eeb7394b800c77
## Why
Token-budget sessions need a way to recover prior conversation context and preserve working state across context-window transitions.
## What changed
- Add direct-model `history` tools for listing windows and items, reading items, and searching conversation contents.
- Add direct-model `notes` tools for listing, reading, searching, appending, and writing persistent notes.
- Route tool calls through the configured Codex backend with trusted session and agent context, bounded request arguments, and truncation-aware output handling.
- Expose the extension when `features.token_budget.use_history_notes_history` is enabled with an OpenAI provider and Codex backend authentication.
## Testing
- Cover tool registration, configuration changes, provider and authentication requirements, backend request context, encrypted output preservation, and request and response limits.
GitOrigin-RevId: 43b259f01014ba3f30803dd7cd5634942407a9bb
## What changed
- Add the canonical agent path as `agent_name` in Responses API turn metadata.
- Fall back to `/root` when a session has no canonical agent path.
- Reserve `agent_name` from client metadata overrides and omit it from MCP request metadata.
## Testing
- Cover root, named subagent, legacy subagent, MCP, and client metadata merge cases.
GitOrigin-RevId: a9adcc079a51beae7d621aba24bcd759ceaa408e
pmccrary-oai