feat: enable sharing of chat sessions

[onematchfox]

Design choices are documented in #1933. Will address/respond to comments either here or there if needed and keep the implementation in sync as we go.

For testing locally, I first installed locally and started a few session as the default user admin@kagent.dev, I then reinstalled with trusted proxy enabled whereby I could test as my real user.

Closes #1933

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

Adds end-to-end “shared session” support via share tokens, including UI affordances to create/manage share links, frontend propagation of X-Share-Token, and backend persistence + enforcement (read-only vs read-write) for shared access.

Changes:

• UI: create/manage share links, show shared-session indicators, and propagate share tokens through chat/task/A2A calls.
• Backend (Go): add session share tables, middleware validation/enforcement, share CRUD endpoints, and session listing enhancements with share metadata.
• Agent runtimes (Python/Go ADK) + Helm/CRDs: optional “share tools” injection and KAGENT_UI_URL plumbing for generating clickable share URLs.

Reviewed changes

Copilot reviewed 54 out of 59 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
ui/src/types/index.ts	Extends Session type with optional share_token and share_read_only.
ui/src/lib/auth.ts	Forwards x-share-token header by default.
ui/src/lib/a2aClient.ts	Allows attaching X-Share-Token to streaming A2A requests; tightens types.
ui/src/lib/tests/auth.test.ts	Updates default-forward-header expectations for share token forwarding.
ui/src/components/sidebars/SessionGroup.tsx	Passes share metadata down to chat items.
ui/src/components/sidebars/ChatItem.tsx	Appends ?share=... to shared-session links and shows shared icon.
ui/src/components/chat/ShareButton.tsx	New client component to create/copy/revoke share links.
ui/src/components/chat/ChatMessage.tsx	Simplifies ask-user submit callback wiring.
ui/src/components/chat/ChatInterface.tsx	Propagates share token through reads/A2A and enforces read-only UI mode; adds ShareButton.
ui/src/components/chat/AskUserDisplay.tsx	Disables ask-user interactions when handlers are absent (read-only mode).
ui/src/components/ToolDisplay.tsx	Disables approve/reject buttons when no handlers (read-only mode).
ui/src/app/agents/[namespace]/[name]/chat/[chatId]/page.tsx	Reads share query param and passes it to ChatInterface (with Suspense).
ui/src/app/actions/sessions.ts	Adds optional shareToken header support for session/task fetches + getSessionWithEvents.
ui/src/app/actions/sessionShares.ts	New server actions for session share CRUD.
python/packages/kagent-adk/tests/unittests/test_share_tools.py	Adds unit tests for Python share tools.
python/packages/kagent-adk/src/kagent/adk/types.py	Adds share_tools flag to AgentConfig and injects share tools when enabled.
python/packages/kagent-adk/src/kagent/adk/tools/share_tools.py	Implements Python ADK share tools and URL generation.
python/packages/kagent-adk/src/kagent/adk/tools/init.py	Exports the new Python share tools.
helm/kagent/values.yaml	Adds controller.externalUrl for setting KAGENT_UI_URL.
helm/kagent/templates/controller-deployment.yaml	Injects KAGENT_UI_URL into controller when configured.
helm/kagent-crds/templates/kagent.dev_sandboxagents.yaml	Adds shareTools field to rendered CRD schema.
helm/kagent-crds/templates/kagent.dev_agents.yaml	Adds shareTools field to rendered CRD schema.
go/core/pkg/migrations/core/000005_session_shares.up.sql	Adds session_share and session_share_access tables.
go/core/pkg/migrations/core/000005_session_shares.down.sql	Adds down migration (currently only drops one table).
go/core/pkg/env/kagent.go	Registers KAGENT_UI_URL env var.
go/core/pkg/auth/share_test.go	Unit tests for ShareContext helpers.
go/core/pkg/auth/share.go	Adds ShareContext storage/retrieval in request context.
go/core/internal/httpserver/server_share_middleware_test.go	Adds tests for share-token middleware behavior.
go/core/internal/httpserver/server.go	Registers share routes and share-token middleware.
go/core/internal/httpserver/middleware.go	Implements share-token validation, read-only enforcement, and access recording.
go/core/internal/httpserver/handlers/sessions_test.go	Extends session handler tests for read_only field + updated list type.
go/core/internal/httpserver/handlers/sessions_share_context_test.go	Adds tests for effective user ID resolution under share context.
go/core/internal/httpserver/handlers/sessions.go	Uses ShareContext for DB lookups + returns read_only in responses.
go/core/internal/httpserver/handlers/session_shares_test.go	Adds tests for session share CRUD handlers.
go/core/internal/httpserver/handlers/session_shares.go	Implements session share CRUD endpoints.
go/core/internal/httpserver/handlers/handlers.go	Wires SessionSharesHandler into handler set.
go/core/internal/httpserver/auth/authn.go	Forces agent upstream calls to use share owner’s X-User-Id when share context present.
go/core/internal/database/queries/sessions.sql	Enhances session listing to include shared sessions and share metadata.
go/core/internal/database/queries/session_shares.sql	Adds SQL queries for share CRUD and access upsert.
go/core/internal/database/client_postgres.go	Implements DB methods for shares + new session list return type.
go/core/internal/controller/translator/agent/manifest_builder.go	Propagates KAGENT_UI_URL into agent pods when set.
go/core/internal/controller/translator/agent/compiler.go	Passes shareTools flag into ADK AgentConfig.
go/core/internal/a2a/manager_test.go	Tests initiated_by injection when share context is present.
go/core/internal/a2a/manager.go	Injects initiated_by metadata for shared-session A2A messages.
go/api/v1alpha2/agent_types.go	Adds shareTools field to Agent CRD Go types.
go/api/database/models.go	Adds SessionWithShareToken and SessionShare models.
go/api/database/client.go	Extends DB client interface with share methods and updated session list signature.
go/api/config/crd/bases/kagent.dev_sandboxagents.yaml	Adds shareTools to generated CRD base.
go/api/config/crd/bases/kagent.dev_agents.yaml	Adds shareTools to generated CRD base.
go/api/adk/types.go	Adds share_tools to ADK AgentConfig JSON handling.
go/adk/pkg/tools/share_tools_test.go	Adds tests for Go ADK share tools.
go/adk/pkg/tools/share_tools.go	Implements Go ADK share tools and URL generation.
go/adk/pkg/runner/adapter.go	Conditionally injects share tools into Go ADK runner.
go/adk/cmd/main.go	Passes HTTP client + kagent URL into runner config for share tools.

Files not reviewed (5)

• go/api/v1alpha2/zz_generated.deepcopy.go: Language not supported
• go/core/internal/database/gen/models.go: Language not supported
• go/core/internal/database/gen/querier.go: Language not supported
• go/core/internal/database/gen/session_shares.sql.go: Language not supported
• go/core/internal/database/gen/sessions.sql.go: Language not supported

Comments suppressed due to low confidence (8)

go/core/pkg/migrations/core/000005_session_shares.down.sql:1

• The down migration drops session_share but not session_share_access. Since session_share_access has a foreign key referencing session_share, dropping session_share first will fail in Postgres (or leave orphaned objects depending on settings). Drop session_share_access first, then session_share (and consider dropping the index too for completeness).
  ui/src/components/chat/ShareButton.tsx:1
• This references window during render. In Next.js App Router, client components can still be pre-rendered on the server, where window is undefined, causing a runtime crash. Compute origin inside an effect (store in state), or guard with typeof window !== \"undefined\" before reading window.location.origin.
  ui/src/components/chat/ChatInterface.tsx:1
• shareReadOnly is only set inside the shareToken branch. If the user navigates from a shared read-only session to a non-shared session without a full remount, shareReadOnly can remain true and incorrectly disable interactions. Reset shareReadOnly to false when shareToken is absent (e.g., at the start of initialization or in the else branch).
  ui/src/components/chat/ChatInterface.tsx:1
• shareReadOnly is only set inside the shareToken branch. If the user navigates from a shared read-only session to a non-shared session without a full remount, shareReadOnly can remain true and incorrectly disable interactions. Reset shareReadOnly to false when shareToken is absent (e.g., at the start of initialization or in the else branch).
  ui/src/components/chat/ChatInterface.tsx:1
• shareReadOnly is only set inside the shareToken branch. If the user navigates from a shared read-only session to a non-shared session without a full remount, shareReadOnly can remain true and incorrectly disable interactions. Reset shareReadOnly to false when shareToken is absent (e.g., at the start of initialization or in the else branch).
  ui/src/components/sidebars/ChatItem.tsx:1
• The share token is inserted into the URL query string without encoding and will be stored in browser history and may leak via referrer headers/logs. At minimum, wrap the token with encodeURIComponent (or build via URLSearchParams) to prevent malformed URLs; consider using a URL fragment (e.g. #share=...) if feasible so the token is not emitted as an HTTP referrer, while still being readable by the client.
  python/packages/kagent-adk/src/kagent/adk/tools/share_tools.py:1
• Docstring says that without KAGENT_UI_URL the function returns only the raw token, but the implementation returns a relative path containing ?share=<token>. Update the docstring to match actual behavior (relative path vs raw token).
  ui/src/components/chat/ShareButton.tsx:1
• This input has no accessible name (no associated <Label> and no aria-label), which makes the share URL harder to discover for screen reader users. Add an aria-label (e.g. "Share link") or associate it with a visible label.

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[onematchfox]

Noticed that the build failed after latest merge; can't replicate the failure locally though so maybe a retry will sort it out.

[supreme-gg-gg]

I've tried this and it works very well, this implementation looks great overall according to the design in #1933. Just some small comments

[supreme-gg-gg]

this should be .Values.ui.externalUrl?

[onematchfox]

Yes, missed that in 52cbb11. Will fix.

[supreme-gg-gg]

For the python adk tool, I think it can be better if we reuse the existing http client which already has token service. This would require moving the tools initialization to _a2a.py instead, something like this:

def create_runner() -> Runner:
    root_agent = self.root_agent_factory()
    if not local and http_client is not None and self.agent_config and self.agent_config.share_tools:
        from kagent.adk.tools.share_tools import CreateShareLinkTool, ListShareLinksTool, DeleteShareLinkTool
        root_agent.tools.extend([
            CreateShareLinkTool(http_client),
            ListShareLinksTool(http_client),
            DeleteShareLinkTool(http_client),
        ])
    ...

so in the tools it can directly use the http client to make requests. This would reduce code duplication and share existing components like how it's done in go adk.

[onematchfox]

Cool - will make it happen

[supreme-gg-gg]

Personally I think it would be helpful to show a table of all share urls created for this session (so the user can copy / delete generated tokens), similar to how the agent can use the list token tool to view them

[onematchfox]

OK. Was torn on this myself... But I guess if the backend supports multiple share links then the UI should reflect that too.

[supreme-gg-gg]

It seems like the A2A contextId is not bound to the shared token, unlike the REST endpoint where getEffectiveUserIDForSession checks that sc.SessionId == sessionID so that it only returns the owner's ID when the token's scoped session is the requested session. For the A2A case it always adds the owner without checking contextID == sc.SessionID. I think this can be added in A2A send methods in manager.go

[onematchfox]

Good catch

[supreme-gg-gg]

I noted in #1933 you mentioned needing <meta name="referrer" content="no-referrer"> in the security considerations section but it hasn't been added here (or in the layout)

[onematchfox]

🙈 Fixed

[supreme-gg-gg]

nit: distinguish token not found from DB operation failure, it's a invalid for expired token only if the error is pgx.ErrNoRows otherwise we should return 500

[onematchfox]

Fair point. Will fix.

[onematchfox]

I've tried this and it works very well, this implementation looks great overall according to the design in #1933. Just some small comments

Thanks for the review. Think I have addressed all your comments. Also merged main which required a bit of reworking due to the a2a libray migration.

[supreme-gg-gg]

Thanks for addressing the comments quickly! lgtm overall