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@cursor review

Can you please add some screenshots of what this looks like with different emojis and icons, and different values for the size parameter of st.logo?

Summary

This PR adds support for Material icons and emojis in st.logo(), allowing users to use icons like :material/home: or emojis like 🏠 in addition to image files. The implementation follows the same pattern used by st.chat_message for avatars, reusing the existing DynamicIcon component on the frontend.

Key changes:

• Added new ImageType enum to the Logo protobuf (IMAGE/EMOJI/ICON)
• Created _process_logo_image() helper in Python to detect input type
• Updated LogoComponent.tsx to render DynamicIcon for icons/emojis
• Added new StyledIconLogo styled component for sizing

Code Quality

Critical Issue: TypeScript Import Error

File: frontend/app/src/components/Logo/LogoComponent.tsx, Line 35

import { IconSize } from "@streamlit/lib"

This import will fail at compile-time because IconSize is not exported from @streamlit/lib's public API (frontend/lib/src/index.ts). The index.ts only exports specific types from the theme module:

export type { EmotionTheme, PresetThemeName, ThemeConfig } from "./theme"

Fix: Change the import to use the internal path alias available in the app package:

import { IconSize } from "~lib/theme"

This is consistent with how other files in the codebase import IconSize (e.g., DynamicIcon.tsx).

Code Structure (Good)

1. Static data structure at module level ✅ - LOGO_SIZE_TO_ICON_SIZE mapping is correctly defined at module level (line 40-44), following the TypeScript best practices.

2. Clean separation of concerns ✅ - The _process_logo_image() helper function in Python cleanly separates the detection logic.

3. Consistent with existing patterns ✅ - The implementation follows the same approach used by st.chat_message for rendering icons/emojis.

Minor Observations

1. StyledIconLogo (styled-components.ts, lines 201-215): Uses == for comparison instead of ===. While this works in TypeScript, it's generally recommended to use strict equality:

   marginTop: size == "small" ? theme.spacing.xs : theme.spacing.twoXS,

   Should be:

   marginTop: size === "small" ? theme.spacing.xs : theme.spacing.twoXS,

   (Note: This is consistent with the existing StyledLogo component, so it matches the codebase style)

2. Type annotation in Python - The _process_logo_image function correctly uses proper return type annotations following the codebase conventions.

Test Coverage

Python Unit Tests ✅

The Python tests in lib/tests/streamlit/commands/logo_test.py are comprehensive:

• test_material_icon - Tests basic material icon usage
• test_emoji - Tests emoji usage
• test_material_icon_with_link - Tests icon with link combination
• test_icon_with_icon_image - Tests mixed image/icon scenario
• test_invalid_material_icon - Tests error handling for invalid icons

All tests include docstrings following the best practices. The tests verify both the image_type field values and the actual image content.

Frontend Unit Tests ✅

The frontend tests in LogoComponent.test.tsx adequately cover the new functionality:

• Tests DynamicIcon rendering when imageType is ICON
• Tests DynamicIcon rendering when imageType is EMOJI
• Tests img tag rendering when imageType is IMAGE (default)
• Tests iconImageType usage when collapsed with mixed types

The tests follow RTL best practices, using getByTestId and asserting on element behavior rather than implementation details.

E2E Tests

No new E2E tests were added. The PR description mentions this is intentional since the feature "relies on existing DynamicIcon E2E coverage." This is acceptable given:

1. The DynamicIcon component already has E2E coverage
2. The existing st_logo E2E tests cover the logo rendering scenarios
3. The unit tests provide adequate coverage for the new icon/emoji detection logic

However, consider adding at least one E2E test case with icon/emoji logos to verify the full integration.

Backwards Compatibility

Assessment: Fully backwards compatible ✅

1. Protobuf changes are additive - The new image_type and icon_image_type fields use the next available field numbers (5 and 6). The default value for the enum is IMAGE = 0, which means existing messages without these fields will default to image behavior.

2. API signature changes are compatible - The image and icon_image parameters now accept str in addition to AtomicImage, which is a widening change. Existing code using image files will continue to work.

3. Frontend gracefully handles missing types - The isIconOrEmoji check defaults to image rendering when the type is unspecified (proto default is 0/IMAGE).

Security & Risk

No security concerns identified. ✅

1. The icon validation uses existing validate_material_icon() function which validates against the known icon set
2. Emoji validation uses the existing is_emoji() function
3. No new external inputs or attack surfaces introduced
4. The DynamicIcon component already handles sanitization for material icons and emojis

Regression risk: Low

• The changes are well-encapsulated
• Existing image-based logos are unaffected (default behavior preserved)
• The reuse of DynamicIcon is a proven component

Recommendations

1. [REQUIRED] Fix the TypeScript import error:

   In frontend/app/src/components/Logo/LogoComponent.tsx, change line 35 from:

   import { IconSize } from "@streamlit/lib"

   to:

   import { IconSize } from "~lib/theme"

2. [OPTIONAL] Consider adding E2E test coverage:

   Add a test case in e2e_playwright/st_logo.py and st_logo_test.py to verify material icon or emoji logo rendering in the full stack, e.g.:

   def icon_logo_subtest():
       st.logo(":material/rocket_launch:")
       st.sidebar.write("Hi")

3. [OPTIONAL] Consider exporting IconSize from @streamlit/lib:

   If IconSize is needed by the app package, it might be worth adding it to the public exports in frontend/lib/src/index.ts for consistency. However, fixing the import to use the internal path alias is the simpler solution.

Verdict

CHANGES REQUESTED: The PR has a critical TypeScript import error that will cause a build failure. The import of IconSize from @streamlit/lib must be fixed to use the internal path alias ~lib/theme before this PR can be merged. All other aspects of the implementation are well-done and follow the codebase conventions.

This is an automated AI review. Please verify the feedback and use your judgment.

Hey @jrieke @lukasmasuch, apologies for going quiet on this one - life got in the way for a bit!

I've made all the updates:

• Screenshots: Added to the PR description showing material icons at different sizes and emoji support
• Edge case tests: Covered invalid icons, empty strings, and invalid input handling
• E2E tests: Added tests for both material icon and emoji logo rendering

Let me know if there's anything else - always happy to help!

@jrieke please can you remove missing:visual-demonstration label or I need to add any more visuals documentation. Thanks

Sorry for the delay. Reviewed the screenshots and they look good, approved from product side! Will send this to our eng team to review.

Summary

Adds emoji and Material icon support to st.logo by extending the Logo proto with image type metadata and rendering icons via DynamicIcon, plus new Python/TS unit tests and e2e snapshots for icon/emoji cases.

Code Quality

• lib/streamlit/commands/logo.py lines 40-77: _process_logo_image sends any non-emoji, non-:material string to image_to_url, which accepts empty or plain strings and returns a media URL. That means st.logo("") and st.logo("hello") will not raise, contradicting the new tests in lib/tests/streamlit/commands/logo_test.py lines 195-203. Add explicit validation for empty/non-file/non-URL strings or revise those tests/docs to align with existing st.image semantics.
• frontend/app/src/components/Logo/LogoComponent.tsx lines 118-149: when appLogo.link is set and the logo is an emoji/icon, the <a> element lacks an accessible name because the icon content is aria-hidden for emojis. This violates the a11y rule for icon-only links and makes the logo link inaccessible.

Test Coverage

Python unit tests cover icon/emoji cases and invalid inputs; frontend unit tests cover icon/emoji rendering and collapsed behavior; e2e snapshots cover icon and emoji logos. The new e2e tests for icon/emoji do not include a “must NOT happen” assertion as recommended in e2e_playwright guidance (e.g., assert no <img> renders when image_type is ICON/EMOJI).

Backwards Compatibility

Proto changes are additive and should be wire-compatible. Note that emoji/icon logos will render as broken images on older frontends that don’t understand image_type if mixed versions are possible.

Security & Risk

No direct security concerns. Accepting arbitrary strings as logo images can still produce invalid media content (broken images) if the string is not a valid file/URL/emoji/icon.

Recommendations

1. Enforce validation in _process_logo_image for empty and non-URL/non-file strings, or update the new tests to match st.image semantics. (lib/streamlit/commands/logo.py, lib/tests/streamlit/commands/logo_test.py)
2. Add an accessible name for the logo link when rendering icon/emoji logos (e.g., aria-label="Logo link" or a label derived from context). (frontend/app/src/components/Logo/LogoComponent.tsx)
3. Add a negative assertion in the new e2e icon/emoji tests to match the e2e best-practice checklist (e.g., no <img> for icon/emoji logos). (e2e_playwright/st_logo_test.py)

Verdict

CHANGES_REQUESTED: Fix the invalid-string handling and the logo link accessibility before merge.

This is an automated AI review using gpt-5.2-codex-high. Please verify the feedback and use your judgment.

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