HTTP middleware

SMOZ builds a robust Middy stack around HTTP handlers. Non‑HTTP flows bypassMiddy entirely.

Defaults (in order)

1. HEAD short‑circuit (200 {} immediately)
2. Header normalization (canonical case)
3. APIGW v1 event normalization
4. Content negotiation (JSON, vendor +json)
5. Safe JSON body parsing (no 415 surprises)
6. Zod validation (event before handler, response after handler)
7. Error exposure + validation→400 mapping
8. http‑error‑handler with your logger
9. CORS (credentials on; preserves computed origin)
10. Preferred media types defaults across phases
11. Response shaper (statusCode/headers/body) + content‑type enforcement
12. Response serializer (JSON and vendor +json)

Customization surfaces

• App level (optional; in App.create):
  • http.defaults: base options (e.g., contentType, logger)
  • http.profiles: named profiles (options + extend/transform)
• Function level (optional; in app.defineFunction):
  • http.profile: choose one profile by name
  • http.options: shallow overrides
  • http.extend: append steps into phases
  • http.transform: insert/replace/remove steps by ID
  • http.replace: phased arrays or a single middleware (advanced)

Invariants

• head first in before
• serializer last in after
• shape precedes serializer
• error-handler only in onError
• If event/response schemas are present, zod-before and zod-after must exist

Examples

Choose a profile and override content type:

app.defineFunction({
  // ...
  http: {
    profile: 'publicJson',
    options: { contentType: 'application/vnd.my+json' },
  },
});
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Insert a header after the response shaper:

import { insertAfter } from '@karmaniverous/smoz';
const mw = {
  after: (req: any) => {
    req.response.headers['X-My'] = 'yes';
  },
};
app.defineFunction({
  // ...
  http: {
    transform: ({ before, after, onError }) => ({
      before,
      after: insertAfter(after, 'shape', mw as any),
      onError,
    }),
  },
});
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Replace (advanced):

app.defineFunction({
  // ...
  http: {
    replace: {
      stack: {
        before: [...],  // include 'head' and 'zod-before' when schemas are present
        after:  [...],  // ensure 'shape' before 'serializer'; include 'zod-after'
        onError: [...], // include 'error-handler' only here
      },
    },
  },
});
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