improvement: enable reading session cache in App Mode (configurable) by jpopesculian · Pull Request #7895 · marimo-team/marimo

jpopesculian · 2026-01-19T16:30:52Z

Implements #7849

Changes

Bug fix: cell_ids was not initialized on the SessionView so cache exports would sometimes be exported out of order. The fix was to emit an UpdateCellIdsNotification on notebook creation
Add a new serve_cached_sessions_in_apps runtime configuration item to use the cache in a read-only manner when running as an application

vercel · 2026-01-19T16:31:49Z

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marimo-docs	Ready	Preview, Comment	Feb 9, 2026 10:24am

dmadisetti

The added cache flags makes sense in the context, but it seems like you'd always wanted cached outputs when auto instantiation is on?

Agreed that the behavior might be somewhat broken now

dmadisetti · 2026-01-26T12:07:58Z

frontend/src/components/app-config/user-config-form.tsx

+                  </FormItem>
+
+                  <FormDescription>
+                    Whether to cache cell outputs to disk and restore them on


This is true by default when auto instantiation is off I'm not sure we need the additional distinction

dmadisetti · 2026-01-26T12:18:32Z

marimo/_runtime/runtime.py

            LOGGER.info("App is already instantiated, skipping instantiation.")
            return

+        cell_ids = [er.cell_id for er in request.execution_requests]


Is this right? Not certain the cellida must be in order. If it is correct can you leave a comment why?

I've updated this to take an explicit cell_ids for clarity. I think because dict keys are ordered in python as far as my knowledge goes, this would be essentially the same, but it seems somewhat fragile, so better to be explicit

mscolnick · 2026-01-26T23:04:03Z

We don't want the config for edit-mode and app-mode to be the same (there are cases you want one without the other).

How about runtime.serve_cached_sessions_in_apps

class RuntimeConfig:
   ...
   serve_cached_sessions_in_apps: NotRequired[bool]

this way we 1) don't need to set a default and 2) we can fallback to False. this will also result in less of a diff footprint.

also we don't need to show this in the UI if this is just deployment configuration (which I assume is your use-case)

Copilot

Pull request overview

Enables app-mode (RUN) sessions to initialize from the on-disk session cache in a read-only manner, and fixes initial cell ordering initialization so cached exports/replays are ordered deterministically.

Changes:

Add cell_ids to CreateNotebookCommand and emit an UpdateCellIdsNotification at notebook instantiation to initialize SessionView.cell_ids.
Introduce CacheMode and run CachingExtension in read-only mode for RUN sessions (configurable via runtime.serve_cached_sessions_in_apps).
Update OpenAPI schema and tests to account for the new cellIds field and caching mode behavior.

Reviewed changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
tests/_session/state/test_session_view.py	Update `CreateNotebookCommand` test fixtures to include `cell_ids`.
tests/_session/extensions/test_extensions.py	Add coverage for read-only caching mode (no writer start; rename ignored).
tests/_server/test_sessions.py	Validate caching enablement + cache mode across EDIT/RUN and config override.
tests/_server/api/endpoints/test_ws.py	Adjust snapshot expectation: first notification is now `update-cell-ids`.
tests/_runtime/test_runtime.py	Update runtime instantiation tests to pass `cell_ids`.
tests/_runtime/test_dotenv.py	Update `CreateNotebookCommand` fixture with `cell_ids`.
tests/_pyodide/test_pyodide_session.py	Update JSON parsing fixture to include `cellIds`.
packages/openapi/src/api.ts	Regenerate TS types for `cellIds` on `CreateNotebookCommand` and new runtime config key.
packages/openapi/api.yaml	Update OpenAPI schema: `cellIds` required on `CreateNotebookCommand`; add `serve_cached_sessions_in_apps`.
marimo/_session/session.py	Configure caching extension by session mode; enable RUN cache read via config.
marimo/_session/extensions/extensions.py	Add `CacheMode` and skip writer start + rename handling in read-only mode.
marimo/_runtime/runtime.py	Broadcast `UpdateCellIdsNotification` at instantiate using `request.cell_ids`.
marimo/_runtime/commands.py	Extend `CreateNotebookCommand` with `cell_ids`.
marimo/_pyodide/bootstrap.py	Populate `cell_ids` when creating notebook in Pyodide.
marimo/_config/config.py	Add `runtime.serve_cached_sessions_in_apps` to config schema/docs.

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Copilot · 2026-02-07T16:06:20Z

marimo/_session/session.py

+        if mode == SessionMode.EDIT:
+            cache_enabled = not auto_instantiate
+            cache_mode = CacheMode.READ_WRITE
+        else:
+            cache_enabled = config_manager.get_config()["runtime"].get(
+                "serve_cached_sessions_in_apps", False
+            )
+            cache_mode = CacheMode.READ


PR description says a new cache_outputs setting was added to control caching, but the implementation here is keyed off runtime.serve_cached_sessions_in_apps and there are no cache_outputs references in the repo. Please either update the PR description to match the actual config knob (and naming), or implement/rename the setting so the behavior is controlled by cache_outputs as described.

Updated PR description

Copilot · 2026-02-07T16:06:20Z

tests/_pyodide/test_pyodide_session.py

        (
            '{"type": "create-notebook", "executionRequests": [{"cellId": "cell-1", "code": "print(1)", "type": "execute-cell"}], '
-            '"setUiElementValueRequest": {"objectIds": [], "values": [], "type": "update-ui-element"}, '
+            '"cellIds": [], "setUiElementValueRequest": {"objectIds": [], "values": [], "type": "update-ui-element"}, '


This create-notebook JSON fixture sets cellIds to an empty list even though executionRequests contains cell-1. Using an empty cellIds list makes the test less representative and could allow regressions in cell ordering (the new behavior depends on cell_ids). Update the payload so cellIds matches the execution request IDs.

Suggested change

'"cellIds": [], "setUiElementValueRequest": {"objectIds": [], "values": [], "type": "update-ui-element"}, '

'"cellIds": ["cell-1"], "setUiElementValueRequest": {"objectIds": [], "values": [], "type": "update-ui-element"}, '

and use a read-only cache for run mode

github-actions · 2026-02-09T20:01:59Z

🚀 Development release published. You may be able to view the changes at https://marimo.app?v=0.19.10-dev11

Fixes #398. Notebooks failed to execute with a `TypeError: Missing required argument 'cell_ids'` when constructing `CreateNotebookCommand` in the LSP session. marimo-team/marimo#7895 introduced a required `cell_ids` field on `CreateNotebookCommand` to fix out-of-order cache exports — the `SessionView` wasn't being initialized with cell IDs, so the caching system didn't know the canonical cell ordering. The marimo-lsp session subclasses the marimo session and constructs `CreateNotebookCommand` directly, so it wasn't updated when the upstream signature changed. This surfaces as a crash on any cell execution attempt since `instantiate()` is called on the first run. The fix passes `cell_ids=tuple(codes.keys())` to match the upstream pattern, and bumps the marimo dependency to >=0.19.10 where this field is required.

…urable) (#7895)" This reverts commit d85e9b7.

…urable) (#7895)" (#8281) This reverts commit d85e9b7. Closes #8272

jpopesculian requested review from Light2Dark, dmadisetti and manzt as code owners January 19, 2026 16:30

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jpopesculian force-pushed the feat-read-only-cache branch from 84b2312 to 51f70b0 Compare January 23, 2026 14:11

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mscolnick added the enhancement New feature or request label Feb 5, 2026

mscolnick changed the title ~~Improvements to session caching~~ improvement: enable reading session cache in App Mode (configurable) Feb 5, 2026

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jpopesculian added 2 commits February 9, 2026 11:22

fix: initialize cell_ids on notebook creation

23abaaf

feat: add the ability to control the cache

b2bbde1

and use a read-only cache for run mode

jpopesculian force-pushed the feat-read-only-cache branch from 703c07d to b2bbde1 Compare February 9, 2026 10:23

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mscolnick merged commit d85e9b7 into marimo-team:main Feb 9, 2026
5 of 6 checks passed

This was referenced Feb 12, 2026

Fix notebook execution crash due to missing cell_ids argument marimo-team/marimo-lsp#399

Merged

Cannot run notebook in VSCode marimo-team/marimo-lsp#398

Closed

mscolnick added a commit that referenced this pull request Feb 12, 2026

Revert "improvement: enable reading session cache in App Mode (config…

1e09f16

…urable) (#7895)" This reverts commit d85e9b7.

mscolnick added a commit that referenced this pull request Feb 12, 2026

Revert "improvement: enable reading session cache in App Mode (config…

c3b6bf0

…urable) (#7895)" (#8281) This reverts commit d85e9b7. Closes #8272

jpopesculian deleted the feat-read-only-cache branch February 12, 2026 20:45

jpopesculian restored the feat-read-only-cache branch February 13, 2026 17:00

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improvement: enable reading session cache in App Mode (configurable)#7895

improvement: enable reading session cache in App Mode (configurable)#7895
mscolnick merged 2 commits intomarimo-team:mainfrom
aqora-io:feat-read-only-cache

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	'"cellIds": [], "setUiElementValueRequest": {"objectIds": [], "values": [], "type": "update-ui-element"}, '
	'"cellIds": ["cell-1"], "setUiElementValueRequest": {"objectIds": [], "values": [], "type": "update-ui-element"}, '

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