diff --git a/public-docs/hub/configuration/hub-yml.md b/public-docs/hub/configuration/hub-yml.md
index 1710f926d..3c8913d73 100644
--- a/public-docs/hub/configuration/hub-yml.md
+++ b/public-docs/hub/configuration/hub-yml.md
@@ -93,18 +93,18 @@ The grammar supports paths, JSON literals, parentheses, `!`, `==`, `!=`, `&&`, `
 
 ### Steps
 
-| Field           | Required | Notes                                                                                                   |
-| --------------- | -------- | ------------------------------------------------------------------------------------------------------- |
-| `id`            | yes      | Lowercase step identifier, unique within the trigger.                                                   |
-| `environment`   | yes      | Environment name or a finite input expression resolving to one.                                         |
-| `max_runtime`   | yes      | Positive step hard limit, up to 24h.                                                                    |
-| `idle_timeout`  | yes      | Positive idle limit, no longer than the step hard limit.                                                |
-| `agent`         | yes      | `provider`, optional `model`, `mode`, and `thinkingOptionId`.                                           |
-| `prompt`        | yes      | Non-empty list of `text` and GitHub-only `include` blocks.                                              |
-| `if`            | no       | Expression deciding whether this ordered step runs.                                                     |
-| `output`        | no       | `{ schema: <JSON Schema> }` for structured `finish_execution`.                                          |
-| `allow_outputs` | no       | Reply capabilities such as `slack.reply`, `discord.reply`, or `github.reply`, each with optional `max`. |
-| `auto_archive`  | no       | Archives the step's agent when it ends.                                                                 |
+| Field           | Required | Notes                                                                                                             |
+| --------------- | -------- | ----------------------------------------------------------------------------------------------------------------- |
+| `id`            | yes      | Lowercase step identifier, unique within the trigger.                                                             |
+| `environment`   | yes      | Environment name or a finite input expression resolving to one.                                                   |
+| `max_runtime`   | yes      | Positive step hard limit, up to 24h.                                                                              |
+| `idle_timeout`  | yes      | Positive idle limit, no longer than the step hard limit.                                                          |
+| `agent`         | yes      | `provider`, optional `model`, `mode`, and `thinkingOptionId`.                                                     |
+| `prompt`        | yes      | Non-empty list of `text` and GitHub-only `include` blocks.                                                        |
+| `if`            | no       | Expression deciding whether this ordered step runs.                                                               |
+| `output`        | no       | `{ schema: <JSON Schema> }` for structured `finish_execution`.                                                    |
+| `allow_outputs` | no       | Registered output capabilities such as `slack.reply` or `discord.reply`, each with optional `max` and `required`. |
+| `auto_archive`  | no       | Archives the step's agent when it ends.                                                                           |
 
 Prompt blocks are objects, not a scalar prompt:
 
@@ -116,6 +116,19 @@ prompt:
 
 Use `${{ paseo.prompt }}`, `${{ paseo.inputs.* }}`, `${{ steps.*.outputs.* }}`, and `${{ values.* }}` in prompts, conditions, and agent selection fields. Provider event payloads are not part of this workflow expression namespace; provider adapters put the normalized request into the prompt and preserve the raw event as evidence.
 
+#### Output capabilities
+
+`allow_outputs` separates permission from obligation. `max` limits how many times a capability may be emitted and defaults to `1`. Set `required: true` when the step must emit that capability at least once before it can finish successfully:
+
+```yaml
+allow_outputs:
+  - type: discord.reply
+    max: 1
+    required: true
+```
+
+Hub counts an actual capability emission; ordinary assistant text does not satisfy a required output. A required declaration must resolve to a registered, available Hub capability for that execution context, or dispatch rejects the step with an actionable configuration error. If delivery fails, the attempt is retryable; if the agent tries to finish first, Hub keeps the execution recoverable and names the concrete output tool before retrying `finish_execution`. A required output must have an effective `max` of at least `1`, or activation rejects the configuration. Omitting `required` preserves optional-output behavior and does not change the agent's permission mode. GitHub-triggered agents reply with their scoped `GH_TOKEN` (for example, through `gh issue comment`) rather than a Hub `github.reply` tool.
+
 ## Prompt partials
 
 `include` paths are relative to `.paseo/partials/` and are resolved at the exact GitHub configuration commit. Hub stores the resolved content and SHA-256 hash in the immutable revision. Missing files, unsafe paths, symlinks, submodules, directories, and nested includes are rejected. Manual configurations cannot use repository partials.
diff --git a/public-docs/hub/faq.md b/public-docs/hub/faq.md
index 2f51f756e..6bea263c8 100644
--- a/public-docs/hub/faq.md
+++ b/public-docs/hub/faq.md
@@ -44,7 +44,7 @@ Dispatch fails and the event is recorded as failed. Nothing is queued, so trigge
 
 ## Can an agent reply back to Slack or Discord?
 
-Yes, with `allow_outputs`. It gets one plain-text thread reply per execution. On GitHub, agents reply through the scoped `GH_TOKEN` they already have, so `gh issue comment` works.
+Yes, with `allow_outputs`. See the [`hub.yml` output capability reference](/docs/hub/configuration/hub-yml#output-capabilities) for reply limits and required outputs. On GitHub, agents reply through the scoped `GH_TOKEN` they already have, so `gh issue comment` works.
 
 ## Can I use it without GitHub?
 
diff --git a/public-docs/hub/triggers/index.md b/public-docs/hub/triggers/index.md
index 1b010816a..d2809739e 100644
--- a/public-docs/hub/triggers/index.md
+++ b/public-docs/hub/triggers/index.md
@@ -88,4 +88,4 @@ Both run. Triggers are not ordered and do not shadow each other, in one configur
 
 ## Replying
 
-Put `allow_outputs` on the step that should reply. The available provider reply types are `slack.reply`, `discord.reply`, and `github.reply`; set `max` when a step needs more than one update. GitHub-triggered agents also receive a scoped GitHub credential for `gh`.
+Put `allow_outputs` on the step that should reply. The Hub provider reply capabilities are `slack.reply` and `discord.reply`; set `max` when a step needs more than one update, or `required: true` when it must emit at least one reply before it can finish. A required type must be registered and available for the execution context. GitHub-triggered agents receive a scoped GitHub credential for `gh` and can comment through that credential instead of a Hub output tool. See the [`hub.yml` output capability reference](/docs/hub/configuration/hub-yml#output-capabilities) for the contract.