diff --git a/rallly/Chart.yaml b/rallly/Chart.yaml
index 43aff9b..2aba2b7 100644
--- a/rallly/Chart.yaml
+++ b/rallly/Chart.yaml
@@ -5,7 +5,7 @@ icon: https://raw.githubusercontent.com/lukevella/rallly/main/apps/landing/publi
 
 type: application
 
-version: 5.0.0+up4.12.3
+version: 6.0.0+up4.12.3
 appVersion: "4.12.3"
 
 maintainers:
diff --git a/rallly/templates/_helpers.tpl b/rallly/templates/_helpers.tpl
index 81cfde3..1360018 100644
--- a/rallly/templates/_helpers.tpl
+++ b/rallly/templates/_helpers.tpl
@@ -114,3 +114,164 @@ template-chart is the reference implementation.
 1
 {{- end -}}
 {{- end -}}
+
+{{/*
+Merge a user-supplied values sub-tree onto a dict of chart defaults so that a
+null / empty override falls back to the defaults instead of erasing them.
+
+Input: dict "defaults" <dict> "given" <dict|nil> "path" <string, optional
+values path used in error messages>. Output: YAML of the merged dict (consume
+it with fromYaml).
+
+Why this exists (issue #99): Helm merges values maps recursively, but an
+override key written without children — e.g. a leftover
+
+  securityContext:
+
+after deleting its last remaining sub-key — is YAML null. Where the chart
+defines a default, Helm treats that null as a deletion of the default; the
+template then renders "securityContext: null": no readOnlyRootFilesystem, no
+dropped capabilities, no allowPrivilegeEscalation: false. The workload starts
+and reports healthy while being unhardened, so nothing points at the mistake.
+The same shape erases a probe (it disappears) or the resources block (no
+requests, no computed limits). This helper defines the opposite semantics: an
+empty block means "chart defaults apply".
+
+Rules:
+  - a nil "given" is treated as an empty dict (all defaults apply).
+  - a key whose override value is null keeps the default (nulls never delete).
+  - a key present in both as a map is merged recursively, so a partially
+    filled block only overrides the keys it actually sets.
+  - a scalar override for a key the defaults define as a map is rejected with
+    a message naming the values path, instead of failing later with a template
+    field error.
+  - any other set value wins as given, including an explicit false or 0 —
+    Helm's "default" and sprig's "mergeOverwrite" would both swallow those
+    zero values, hence the explicit kindIs "invalid" nil check.
+  - keys only present in the override are passed through unchanged.
+
+NOTE: like the helpers above, this is duplicated into every chart's
+templates/_helpers.tpl with the chart's name as define prefix, because charts
+in this repo deliberately have no dependencies.
+*/}}
+{{- define "rallly.defaultedDict" -}}
+{{- $defaults := .defaults | default dict -}}
+{{- $given := .given -}}
+{{- $path := .path | default "value" -}}
+{{- if kindIs "invalid" $given -}}
+{{- $given = dict -}}
+{{- end -}}
+{{- if not (kindIs "map" $given) -}}
+{{- fail (printf "%s must be a mapping or null, got %s (%v)" $path (kindOf $given) $given) -}}
+{{- end -}}
+{{- $out := deepCopy $defaults -}}
+{{- range $key, $value := $given -}}
+{{- if not (kindIs "invalid" $value) -}}
+{{- $default := index $defaults $key -}}
+{{- if and (kindIs "map" $value) (kindIs "map" $default) -}}
+{{- $_ := set $out $key (fromYaml (include "rallly.defaultedDict" (dict "defaults" $default "given" $value "path" (printf "%s.%s" $path $key)))) -}}
+{{- else if kindIs "map" $default -}}
+{{- fail (printf "%s.%s must be a mapping or null, got %s (%v)" $path $key (kindOf $value) $value) -}}
+{{- else -}}
+{{- $_ := set $out $key $value -}}
+{{- end -}}
+{{- end -}}
+{{- end -}}
+{{- toYaml $out -}}
+{{- end -}}
+
+{{/*
+Pick one sub-block out of a values block that may itself be null.
+
+Input: dict "block" <dict|nil> "key" <string> "path" <string>.
+Returns YAML of dict "value" <the sub-block, may be nil>, after rejecting a
+non-mapping block with a message that names the values path. Needed because
+".Values.rallly.securityContext" can itself be erased.
+*/}}
+{{- define "rallly.subBlock" -}}
+{{- $block := .block -}}
+{{- if kindIs "invalid" $block -}}
+{{- $block = dict -}}
+{{- end -}}
+{{- if not (kindIs "map" $block) -}}
+{{- fail (printf "%s must be a mapping or null, got %s (%v)" .path (kindOf $block) $block) -}}
+{{- end -}}
+{{- toYaml (dict "value" (index $block .key)) -}}
+{{- end -}}
+
+{{/*
+The effective security contexts, probes and resources (issue #99).
+
+The defaults below MUST stay in sync with the corresponding blocks in
+values.yaml, which stays the documented, user-facing place for them; this copy
+is only the fallback for the case where an override has erased the block.
+
+The probes address the container port by its name ("http"), so a rebuilt
+default probe needs no further context.
+
+Note on the container context: no "add:" key is defined here either. An empty
+list item under it renders as a null entry, which is what Trivy reported as
+AVD-KSV-0022 for the older deployed chart version (#84).
+*/}}
+{{- define "rallly.podSecurityContext" -}}
+{{- $given := (fromYaml (include "rallly.subBlock" (dict "block" . "key" "pod" "path" "rallly.securityContext"))).value -}}
+{{- $defaults := dict
+      "runAsNonRoot" true
+      "runAsUser" 20000
+      "runAsGroup" 1000
+      "fsGroup" 1000
+      "fsGroupChangePolicy" "Always" -}}
+{{- include "rallly.defaultedDict" (dict "defaults" $defaults "given" $given "path" "rallly.securityContext.pod") -}}
+{{- end -}}
+
+{{- define "rallly.containerSecurityContext" -}}
+{{- $given := (fromYaml (include "rallly.subBlock" (dict "block" . "key" "container" "path" "rallly.securityContext"))).value -}}
+{{- $defaults := dict
+      "allowPrivilegeEscalation" false
+      "readOnlyRootFilesystem" true
+      "runAsNonRoot" true
+      "capabilities" (dict "drop" (list "ALL")) -}}
+{{- include "rallly.defaultedDict" (dict "defaults" $defaults "given" $given "path" "rallly.securityContext.container") -}}
+{{- end -}}
+
+{{- define "rallly.livenessProbe" -}}
+{{- $defaults := dict
+      "httpGet" (dict "path" "/" "port" "http")
+      "periodSeconds" 10
+      "timeoutSeconds" 5
+      "failureThreshold" 3 -}}
+{{- include "rallly.defaultedDict" (dict "defaults" $defaults "given" . "path" "rallly.livenessProbe") -}}
+{{- end -}}
+
+{{- define "rallly.readinessProbe" -}}
+{{- $defaults := dict
+      "httpGet" (dict "path" "/" "port" "http")
+      "periodSeconds" 10
+      "timeoutSeconds" 5
+      "failureThreshold" 3 -}}
+{{- include "rallly.defaultedDict" (dict "defaults" $defaults "given" . "path" "rallly.readinessProbe") -}}
+{{- end -}}
+
+{{- define "rallly.startupProbe" -}}
+{{- $defaults := dict
+      "httpGet" (dict "path" "/" "port" "http")
+      "periodSeconds" 5
+      "timeoutSeconds" 5
+      "failureThreshold" 30 -}}
+{{- include "rallly.defaultedDict" (dict "defaults" $defaults "given" . "path" "rallly.startupProbe") -}}
+{{- end -}}
+
+{{/*
+The effective resources block, fed into the resources helper above so that an
+erased "resources:" still yields the chart's requests and computed limits
+instead of a container without any resource accounting. That matters more here
+than elsewhere: the Next.js cache is an emptyDir, and its usage counts against
+the container's ephemeral-storage limit.
+*/}}
+{{- define "rallly.effectiveResources" -}}
+{{- $defaults := dict
+      "limitFactor" 3
+      "requests" (dict "cpu" 0.1 "memory" "512Mi" "ephemeral-storage" "100Mi") -}}
+{{- $merged := fromYaml (include "rallly.defaultedDict" (dict "defaults" $defaults "given" . "path" "rallly.resources")) -}}
+{{- include "rallly.resources" $merged -}}
+{{- end -}}
diff --git a/rallly/templates/rallly.deployment.yaml b/rallly/templates/rallly.deployment.yaml
index 8a7eaf3..ac4dfdf 100644
--- a/rallly/templates/rallly.deployment.yaml
+++ b/rallly/templates/rallly.deployment.yaml
@@ -17,14 +17,18 @@ spec:
     spec:
       automountServiceAccountToken: false
       securityContext:
-        {{- toYaml .Values.rallly.securityContext.pod | nindent 8 }}
+        {{- include "rallly.podSecurityContext" .Values.rallly.securityContext | nindent 8 }}
       containers:
         - name: {{ .Release.Name }}-{{ .Chart.Name }}-deployment
           image: "lukevella/rallly:{{ .Chart.AppVersion }}"
           imagePullPolicy: IfNotPresent
           env:
+            # ingress.domain is not a pure Ingress value: it is also the app's
+            # public base URL, so it stays required even when the Ingress is
+            # switched off (an empty value would render "https://" and break
+            # every generated link silently).
             - name: NEXT_PUBLIC_BASE_URL
-              value: "https://{{ .Values.ingress.domain }}"
+              value: "https://{{ required "A Domain/Host must be provided (ingress.domain)" .Values.ingress.domain }}"
             - name: SECRET_PASSWORD
               valueFrom:
                 secretKeyRef:
@@ -141,15 +145,15 @@ spec:
               protocol: TCP
               name: http
           livenessProbe:
-            {{ toYaml .Values.rallly.livenessProbe | nindent 12}}
+            {{- include "rallly.livenessProbe" .Values.rallly.livenessProbe | nindent 12 }}
           readinessProbe:
-            {{ toYaml .Values.rallly.readinessProbe | nindent 12}}
+            {{- include "rallly.readinessProbe" .Values.rallly.readinessProbe | nindent 12 }}
           startupProbe:
-            {{ toYaml .Values.rallly.startupProbe | nindent 12}}
+            {{- include "rallly.startupProbe" .Values.rallly.startupProbe | nindent 12 }}
           resources:
-            {{- include "rallly.resources" .Values.rallly.resources | nindent 12 }}
+            {{- include "rallly.effectiveResources" .Values.rallly.resources | nindent 12 }}
           securityContext:
-            {{- toYaml .Values.rallly.securityContext.container | nindent 12 }}
+            {{- include "rallly.containerSecurityContext" .Values.rallly.securityContext | nindent 12 }}
           volumeMounts:
             # Next.js writes prerendered pages and optimized images into its
             # cache directory; with a read-only root filesystem this must be a
diff --git a/rallly/templates/rallly.ingress.yaml b/rallly/templates/rallly.ingress.yaml
index 6c22769..a9387ff 100644
--- a/rallly/templates/rallly.ingress.yaml
+++ b/rallly/templates/rallly.ingress.yaml
@@ -1,3 +1,4 @@
+{{- if .Values.ingress.enabled }}
 apiVersion: networking.k8s.io/v1
 kind: Ingress
 metadata:
@@ -24,3 +25,4 @@ spec:
     - hosts:
         - {{ required "A Domain/Host must be provided" .Values.ingress.domain }}
       secretName: tls-{{ .Release.Name }}-{{ .Chart.Name }}-ingress
+{{- end }}
diff --git a/rallly/values.schema.json b/rallly/values.schema.json
new file mode 100644
index 0000000..888a1e7
--- /dev/null
+++ b/rallly/values.schema.json
@@ -0,0 +1,232 @@
+{
+  "$schema": "https://json-schema.org/draft-07/schema#",
+  "title": "rallly values",
+  "description": "Strict values schema (issue #68). additionalProperties is false on every chart-owned object level, so a key that the chart does not read is rejected at render time instead of being silently ignored. The only objects that stay open are the ones passed verbatim into the Kubernetes pod spec (probes, security contexts, global) - the chart does not interpret their contents, so it cannot judge which keys are meaningful. The hardening, probe and resources blocks additionally accept null, because an erased block falls back to the chart defaults (issue #99).",
+  "type": "object",
+  "additionalProperties": false,
+  "properties": {
+    "global": {
+      "description": "Helm's conventional cross-chart values. Unused by this chart, kept open so an umbrella install cannot break on it.",
+      "type": "object"
+    },
+    "scaleDown": {
+      "type": "boolean"
+    },
+    "secrets": {
+      "type": "object",
+      "additionalProperties": false,
+      "properties": {
+        "ralllySecretRef": {
+          "type": ["string", "null"]
+        },
+        "oidcSecretRef": {
+          "type": ["string", "null"]
+        },
+        "databaseSecretRef": {
+          "type": ["string", "null"]
+        },
+        "smtpSecretRef": {
+          "type": ["string", "null"]
+        }
+      }
+    },
+    "rallly": {
+      "type": "object",
+      "additionalProperties": false,
+      "properties": {
+        "replicas": {
+          "type": "integer",
+          "minimum": 0
+        },
+        "smtp": {
+          "type": "object",
+          "additionalProperties": false,
+          "properties": {
+            "enabled": {
+              "type": "boolean"
+            },
+            "rejectUnauthorized": {
+              "description": "Passed to the app as SMTP_REJECT_UNAUTHORIZED. Read by the chart but deliberately without a default in values.yaml - see the note in the PR that introduced this schema.",
+              "type": ["boolean", "string", "null"]
+            }
+          }
+        },
+        "allowedEmails": {
+          "type": ["string", "null"]
+        },
+        "supportEmail": {
+          "type": ["string", "null"]
+        },
+        "oidc": {
+          "type": "object",
+          "additionalProperties": false,
+          "properties": {
+            "name": {
+              "type": ["string", "null"]
+            },
+            "pictureClaimPath": {
+              "type": ["string", "null"]
+            },
+            "emailClaimPath": {
+              "type": ["string", "null"]
+            },
+            "nameClaimPath": {
+              "type": ["string", "null"]
+            }
+          }
+        },
+        "cache": {
+          "description": "The writable emptyDir mounted over the Next.js cache directory. Not null-safe on purpose: cache.path is required(), so an erased block fails loudly instead of silently (issue #99 covers only the silent class).",
+          "type": "object",
+          "additionalProperties": false,
+          "properties": {
+            "path": {
+              "type": ["string", "null"]
+            },
+            "sizeLimit": {
+              "type": ["string", "number", "null"]
+            }
+          }
+        },
+        "securityContext": {
+          "$ref": "#/definitions/securityContext"
+        },
+        "env": {
+          "$ref": "#/definitions/env"
+        },
+        "resources": {
+          "$ref": "#/definitions/resources"
+        },
+        "livenessProbe": {
+          "$ref": "#/definitions/probe"
+        },
+        "readinessProbe": {
+          "$ref": "#/definitions/probe"
+        },
+        "startupProbe": {
+          "$ref": "#/definitions/probe"
+        }
+      }
+    },
+    "ingress": {
+      "type": "object",
+      "additionalProperties": false,
+      "properties": {
+        "enabled": {
+          "description": "Gates the whole Ingress template (issue #93). false omits the Ingress and makes clusterIssuer unnecessary - but NOT domain, which is also the app's public base URL.",
+          "type": "boolean"
+        },
+        "clusterIssuer": {
+          "type": ["string", "null"]
+        },
+        "domain": {
+          "type": ["string", "null"]
+        },
+        "className": {
+          "type": ["string", "null"]
+        },
+        "annotations": {
+          "description": "Extra Ingress annotations, merged with the cert-manager annotation the chart always sets. Free-form keys by nature.",
+          "type": "object"
+        }
+      }
+    }
+  },
+  "definitions": {
+    "resources": {
+      "description": "May be null / empty: the chart then falls back to its default requests and computed limits (issue #99) instead of rendering a container without resource accounting.",
+      "type": ["object", "null"],
+      "additionalProperties": false,
+      "properties": {
+        "limitFactor": {
+          "type": "number",
+          "exclusiveMinimum": 0
+        },
+        "requests": {
+          "$ref": "#/definitions/resourceList"
+        },
+        "limits": {
+          "$ref": "#/definitions/resourceList"
+        }
+      }
+    },
+    "resourceList": {
+      "type": ["object", "null"],
+      "additionalProperties": false,
+      "properties": {
+        "cpu": {
+          "type": ["string", "number", "null"]
+        },
+        "memory": {
+          "type": ["string", "number", "null"]
+        },
+        "ephemeral-storage": {
+          "type": ["string", "number", "null"]
+        },
+        "ephemeralStorage": {
+          "type": ["string", "number", "null"]
+        }
+      }
+    },
+    "env": {
+      "type": "array",
+      "items": {
+        "type": "object",
+        "additionalProperties": false,
+        "required": ["name"],
+        "properties": {
+          "name": {
+            "type": "string"
+          },
+          "value": {
+            "type": "string"
+          },
+          "valueFrom": {
+            "type": "object",
+            "additionalProperties": false,
+            "properties": {
+              "secretKeyRef": {
+                "$ref": "#/definitions/keyRef"
+              },
+              "configMapKeyRef": {
+                "$ref": "#/definitions/keyRef"
+              }
+            }
+          }
+        }
+      }
+    },
+    "keyRef": {
+      "type": "object",
+      "additionalProperties": false,
+      "required": ["name", "key"],
+      "properties": {
+        "name": {
+          "type": "string"
+        },
+        "key": {
+          "type": "string"
+        }
+      }
+    },
+    "securityContext": {
+      "description": "May be null / empty at any level: the chart then falls back to its hardening defaults (issue #99) instead of rendering an unhardened workload.",
+      "type": ["object", "null"],
+      "additionalProperties": false,
+      "properties": {
+        "pod": {
+          "description": "Merged onto the chart's pod hardening defaults and rendered as the pod's securityContext; kept open because the chart does not interpret the individual fields.",
+          "type": ["object", "null"]
+        },
+        "container": {
+          "description": "Merged onto the chart's container hardening defaults and rendered as the container's securityContext; kept open because the chart does not interpret the individual fields.",
+          "type": ["object", "null"]
+        }
+      }
+    },
+    "probe": {
+      "description": "Merged onto the chart's probe defaults and rendered as a container probe; kept open because the chart does not interpret the individual fields. May be null / empty, which means the defaults apply (issue #99) rather than the probe disappearing.",
+      "type": ["object", "null"]
+    }
+  }
+}
diff --git a/rallly/values.yaml b/rallly/values.yaml
index 088287d..7786c95 100644
--- a/rallly/values.yaml
+++ b/rallly/values.yaml
@@ -101,6 +101,11 @@ rallly:
     failureThreshold: 30
 
 ingress:
+  # Set to false to omit the Ingress entirely. Note that ingress.domain stays
+  # required even then: it is also the app's public base URL
+  # (NEXT_PUBLIC_BASE_URL), not just the Ingress host. Only clusterIssuer
+  # becomes unnecessary.
+  enabled: true
   clusterIssuer: null
   domain: null
   className: nginx