fix(ui): preserve full AgentCore runtime ARN in agent edit form

[yassin-berriai]

TLDR

Problem this solves:

• Editing an AgentCore agent showed a truncated runtime ARN and silently corrupted it on save

How it solves it:

• Recovers the ARN from the stored model string with a regex instead of matching split("/") segments by position
• Rejects a malformed or truncated ARN before save with a clear inline error

User Flow

Before: opening an AgentCore agent's settings and saving without any changes corrupts its runtime ARN

1. Admin opens the Agents page, clicks an AgentCore agent, then "Edit Settings"
2. The "Agent Runtime ARN" field shows only arn:aws:bedrock-agentcore:eu-central-1:123456789012:runtime, missing everything after runtime/
3. They click "Save Changes" without editing the field
4. The agent's stored ARN is now permanently truncated, and calls through this agent fail

After: the same flow shows and saves the complete ARN every time, and a bad value is caught before it can be saved

1. Admin opens the Agents page, clicks an AgentCore agent, then "Edit Settings"
2. The "Agent Runtime ARN" field shows the complete ARN, including the resource id after runtime/
3. They click "Save Changes" without editing the field
4. Reopening "Edit Settings" shows the identical, complete ARN
5. If they instead type a truncated or malformed ARN and click "Save Changes", the field shows a validation error and nothing is saved

Relevant issues

Linear ticket

Resolves LIT-6737

Pre-Submission checklist

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• I have added meaningful tests
• The handful of test files covering my change pass locally, e.g. uv run pytest tests/test_litellm/<your_test_file>.py -v. Leave the suites (make test-unit-*, make test-unit) to CI: it finishes in ~15 minutes where a laptop takes an hour or more
• My PR passes all required CI/CD checks (e.g., lint, schema.d.ts sync check, etc.)
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Delays in PR merge?

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Screenshots / Proof of Fix

Setup shared across cases: local proxy + Postgres, and the dashboard dev server, both from this branch. An AgentCore agent was created through POST /v1/agents with litellm_params.model set to bedrock/agentcore/arn:aws:bedrock-agentcore:eu-central-1:123456789012:runtime/hosted_agent_4vm3i-BaTdfOELAs, then edited through the Admin UI (Agents -> agent -> Settings -> Edit Settings).

Before (a677242)

Edit form displays and saves the runtime ARN

1. Open Settings -> Edit Settings for the agent. The "Agent Runtime ARN" field renders truncated, missing the resource id after runtime/:
   
   
2. Click "Save Changes" without editing anything. The toast confirms the save, and GET /v1/agents/{agent_id} now returns the truncated value:

   $ curl -s http://127.0.0.1:16737/v1/agents/071bfa0d-0a38-46ec-9e10-142ce2fe90a9 -H "Authorization: Bearer $MASTER_KEY" | jq -r .litellm_params.model
   bedrock/agentcore/arn:aws:bedrock-agentcore:eu-central-1:123456789012:runtime
   

   The resource id is gone for good and the agent is corrupted

Malformed ARN is rejected before saving

1. There is no client-side validation on this commit, so the exact same click in the previous case is the "before" for this case too: whatever the field holds, truncated or otherwise, saves silently with no warning

After (443f8df)

Edit form displays and saves the runtime ARN

1. Open Settings -> Edit Settings for a freshly created agent carrying the same full ARN. The field now renders the complete value:
   
   
2. Click "Save Changes" without editing anything. GET /v1/agents/{agent_id} returns the byte-identical full ARN:

   $ curl -s http://127.0.0.1:16737/v1/agents/f3b2207f-88b6-49d3-b841-f65e524424a3 -H "Authorization: Bearer $MASTER_KEY" | jq -r .litellm_params.model
   bedrock/agentcore/arn:aws:bedrock-agentcore:eu-central-1:123456789012:runtime/hosted_agent_4vm3i-BaTdfOELAs
   

3. Reopening "Edit Settings" shows the same complete ARN, confirming the round trip:
   

Malformed ARN is rejected before saving

1. In the same edit form, replace the ARN with a truncated value (arn:aws:bedrock-agentcore:eu-central-1:123456789012:runtime, missing the resource id) and click "Save Changes". The field shows a validation error and the request never goes out:
   
2. GET /v1/agents/{agent_id} confirms the stored value is unchanged (still the full ARN from the previous case)

Type

🐛 Bug Fix

Caveats

Low

• The validator checks the overall shape of a Bedrock AgentCore runtime ARN (partition, region, account id, and a non-empty resource id after runtime/); it is not a full ARN grammar validator, matching the acceptance criteria's ask for a lightweight check

Final Attestation

• The tests check the right things, including the edge cases, and regressions in the respective real-world customer use-cases are not possible after this PR

[CLAassistant]

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[codspeed]

Merging this PR will not alter performance

✅ 31 untouched benchmarks

---

_{Comparing litellm_agent_arn_truncation_fix (443f8df) with litellm_internal_staging (987ab76)¹}

Footnotes

1. No successful run was found on litellm_internal_staging (d2fe8af) during the generation of this report, so 987ab76 was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

[greptile-apps]

Greptile Summary

The PR preserves complete AgentCore runtime ARNs when dynamic agent data is loaded into the edit form and adds client-side ARN validation.

• Replaces positional path parsing with immutable template-based extraction.
• Guards malformed server-provided validation patterns so they cannot crash form rendering.
• Adds backend metadata fields and regression coverage for ARN round trips and validation.

Confidence Score: 5/5

The PR appears safe to merge.

No blocking failure remains; both previously reported issues are resolved at the current head.

Important Files Changed

Filename	Overview
ui/litellm-dashboard/src/app/(dashboard)/agents/_components/agent_type_utils.ts	The immutable split/map parser correctly preserves slash-containing values for all currently configured single-placeholder model templates.
ui/litellm-dashboard/src/app/(dashboard)/agents/_components/dynamic_agent_form_fields.tsx	Regex construction is now guarded, fully resolving the prior malformed-pattern render failure while retaining required-field validation.
litellm/proxy/public_endpoints/agent_create_fields.json	AgentCore metadata now supplies a valid runtime ARN pattern and actionable validation message.
ui/litellm-dashboard/src/app/(dashboard)/agents/_components/agent_info.integration.test.tsx	Integration tests cover full ARN preservation, truncated ARN rejection, and malformed validation-pattern handling.

_{Reviews (2): Last reviewed commit: "fix(ui): preserve full AgentCore runtime..." | Re-trigger Greptile}

[yassin-berriai]

@greptileai please review the current head 443f8df. Addressed both round-1 findings: extractModelTemplateValues now splits on the placeholder pattern instead of mutable accumulators (agent_type_utils.ts), and the validation_pattern regex construction is wrapped in try/catch with a new regression test covering a malformed pattern string (dynamic_agent_form_fields.tsx).

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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