fix(envvars): resolution standardized

[icecrasher321]

Summary

• Resolution varied between trigger paths causing confusion.
• Double resolution of env vars in some, and special handling for response format that was redundant.
• Client/Server side mixing of responsibilities hidden by dynamic imports.
• Highlighting of env vars should be in line with variable resolution. If we're "trying" to resolve -- should be blue, otherwise not highlighted.

Type of Change

• Bug fix
• Other: Refactor

Testing

Tested manually

Checklist

• Code follows project style guidelines
• Self-reviewed my changes
• Tests added/updated and passing
• No new warnings introduced
• I confirm that I have read and agree to the terms outlined in the Contributor License Agreement (CLA)

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1 Skipped Deployment

Project	Deployment	Review	Updated (UTC)
docs	Skipped		Jan 23, 2026 10:20pm

[icecrasher321]

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[greptile-apps]

Greptile Summary

Standardized environment variable resolution across webhook, workflow, and MCP execution paths by consolidating duplicate resolution logic into shared utilities.

Key improvements:

• Introduced ENV_VAR_RESOLVE_DEFAULTS constant in executor/utils/reference-validation.ts to ensure consistent resolution behavior across all contexts (exact match, embedded patterns, whitespace tolerance, missing key handling)
• Fixed double resolution bug in webhook creation flow by preserving original config and only merging external subscription additions (apps/sim/app/api/webhooks/route.ts:303-308)
• Removed redundant response format special handling in serializer that was causing extra resolution passes
• Created server-only lib/mcp/resolve-config.ts and client-safe lib/mcp/shared.ts for proper client/server separation in MCP code
• Deleted preflight env var validation (lib/workflows/executor/preflight.ts) which was causing confusion and unnecessary validation passes
• Enhanced frontend highlighting to only highlight env vars that actually exist in workspace/personal settings

Client/server responsibility clarification:

• Server-side: resolveMcpConfigEnvVars, resolveEnvVarsInObject handle database access and resolution
• Client-side: useAvailableEnvVarKeys hook provides env var key lists for UI highlighting without needing decrypted values
• MCP service and test-connection endpoint now share the same resolution utility, with test endpoint using non-strict mode

The refactor removes 724 lines and adds 382 lines, eliminating inconsistencies where some paths double-resolved env vars while others had special handling.

Confidence Score: 4/5

• Safe to merge with minor style improvement recommended for closure ordering in lib/mcp/resolve-config.ts
• The refactor successfully consolidates env var resolution logic and removes problematic double-resolution paths. Code is well-tested manually according to the PR checklist. The only concern is a confusing closure scope ordering pattern in resolveMcpConfigEnvVars where a function references a variable declared later (technically valid JS but poor readability). All other changes follow clear architectural improvements: standardized defaults, proper client/server separation, and simplified resolution paths.
• Pay attention to apps/sim/lib/mcp/resolve-config.ts for the closure scope ordering pattern. Consider moving the envVars initialization before the resolveValue function definition for better readability.

Important Files Changed

Filename	Overview
apps/sim/lib/mcp/resolve-config.ts	New server-side MCP config resolver with shared utility for env var resolution, has closure scope ordering issue
apps/sim/executor/utils/reference-validation.ts	Added standardized defaults for env var resolution across all contexts, improving consistency
apps/sim/lib/webhooks/env-resolver.ts	Simplified to delegate to shared resolveEnvVarReferences utility with deep:true for nested structures
apps/sim/lib/environment/utils.ts	Removed preflight validation functions, added decryption failure tracking with proper logging
apps/sim/lib/execution/preprocessing.ts	Removed preflightEnvVars option and related validation, simplifying the preprocessing flow
apps/sim/app/api/webhooks/route.ts	Fixed double resolution of env vars by preserving original config and only merging external subscription additions

Sequence Diagram

sequenceDiagram
    participant Client as Client Component
    participant API as API Route
    participant Resolver as Env Resolver
    participant Utils as Env Utils
    participant DB as Database
    participant Core as resolveEnvVarReferences

    Note over Client,Core: Standardized Flow (After PR)

    rect rgb(220, 240, 220)
    Note right of Client: Webhook Creation Path
    Client->>API: POST /api/webhooks
    API->>Resolver: resolveEnvVarsInObject(config)
    Resolver->>Utils: getEffectiveDecryptedEnv(userId, workspaceId)
    Utils->>DB: Query personal + workspace env vars
    DB-->>Utils: Encrypted env vars
    Utils->>Utils: Decrypt all env vars
    Utils-->>Resolver: Decrypted env vars map
    Resolver->>Core: resolveEnvVarReferences(config, envVars, {deep:true})
    Core->>Core: Apply ENV_VAR_RESOLVE_DEFAULTS
    Core-->>Resolver: Resolved config
    Resolver-->>API: Resolved config (single pass)
    API->>API: Store original + external additions
    Note over API: No double resolution
    end

    rect rgb(220, 220, 240)
    Note right of Client: MCP Config Resolution Path
    Client->>API: POST /api/mcp/servers/test-connection
    API->>Utils: resolveMcpConfigEnvVars(config, {strict:false})
    Utils->>Utils: getEffectiveDecryptedEnv(userId, workspaceId)
    Utils->>Core: resolveEnvVarReferences(url, envVars)
    Core->>Core: Apply ENV_VAR_RESOLVE_DEFAULTS
    Core-->>Utils: Resolved url
    Utils->>Core: resolveEnvVarReferences(headers[key], envVars)
    Core-->>Utils: Resolved header value
    Utils-->>API: {config, missingVars}
    Note over API: Consistent resolution across MCP service & test endpoint
    end

    rect rgb(240, 220, 220)
    Note right of Core: Removed Paths (Before PR)
    Note over API,Core: ❌ Preflight env var validation (deleted)
    Note over API,Core: ❌ Double resolution in serializer (removed)
    Note over API,Core: ❌ Special response format handling (removed)
    end

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