feat(agents): add Hephaestus - autonomous deep worker agent (#1287)

* refactor(keyword-detector): split constants into domain-specific modules

* feat(shared): add requiresAnyModel and isAnyFallbackModelAvailable

* feat(config): add hephaestus to agent schemas

* feat(agents): add Hephaestus autonomous deep worker

* feat(cli): update model-fallback for hephaestus support

* feat(plugin): add hephaestus to config handler with ordering

* test(delegate-task): update tests for hephaestus agent

* docs: update AGENTS.md files for hephaestus

* docs: add hephaestus to READMEs

* chore: regenerate config schema

* fix(delegate-task): bypass requiresModel check when user provides explicit config

* docs(hephaestus): add 4-part context structure for explore/librarian prompts

* docs: fix review comments from cubic (non-breaking changes)

- Move Hephaestus from Primary Agents to Subagents (uses own fallback chain)
- Fix Hephaestus fallback chain documentation (claude-opus-4-5 → gemini-3-pro)
- Add settings.local.json to claude-code-hooks config sources
- Fix delegate_task parameters in ultrawork prompt (agent→subagent_type, background→run_in_background, add load_skills)
- Update line counts in AGENTS.md (index.ts: 788, manager.ts: 1440)

* docs: fix additional documentation inconsistencies from oracle review

- Fix delegate_task parameters in Background Agents example (docs/features.md)
- Fix Hephaestus fallback chain in root AGENTS.md to match model-requirements.ts

* docs: clarify Hephaestus has no fallback (requires gpt-5.2-codex only)

Hephaestus uses requiresModel constraint - it only activates when gpt-5.2-codex
is available. The fallback chain in code is unreachable, so documentation
should not mention fallbacks.

* fix(hephaestus): remove unreachable fallback chain entries

Hephaestus has requiresModel: gpt-5.2-codex which means the agent only
activates when that specific model is available. The fallback entries
(claude-opus-4-5, gemini-3-pro) were unreachable and misleading.

---------

Co-authored-by: justsisyphus <justsisyphus@users.noreply.github.com>

README.md

@@ -114,7 +114,8 @@ Yes, technically possible. But I cannot recommend using it.
     - [It's the Age of Agents](#its-the-age-of-agents)
     - [🪄 The Magic Word: `ultrawork`](#-the-magic-word-ultrawork)
     - [For Those Who Want to Read: Meet Sisyphus](#for-those-who-want-to-read-meet-sisyphus)
-      - [Just Install It.](#just-install-it)
+      - [Just Install This](#just-install-this)
+    - [For Those Who Want Autonomy: Meet Hephaestus](#for-those-who-want-autonomy-meet-hephaestus)
   - [Installation](#installation)
     - [For Humans](#for-humans)
     - [For LLM Agents](#for-llm-agents)
@@ -193,6 +194,7 @@ Meet our main agent: Sisyphus (Opus 4.5 High). Below are the tools Sisyphus uses
 *Everything below is customizable. Take what you want. All features are enabled by default. You don't have to do anything. Battery Included, works out of the box.*
 
 - Sisyphus's Teammates (Curated Agents)
+  - Hephaestus: Autonomous deep worker, goal-oriented execution (GPT 5.2 Codex Medium) — *The Legitimate Craftsman*
   - Oracle: Design, debugging (GPT 5.2 Medium)
   - Frontend UI/UX Engineer: Frontend development (Gemini 3 Pro)
   - Librarian: Official docs, open source implementations, codebase exploration (Claude Sonnet 4.5)
@@ -234,6 +236,24 @@ Need to look something up? It scours official docs, your entire codebase history
 
 If you don't want all this, as mentioned, you can just pick and choose specific features.
 
+### For Those Who Want Autonomy: Meet Hephaestus
+
+![Meet Hephaestus](.github/assets/hephaestus.png)
+
+In Greek mythology, Hephaestus was the god of forge, fire, metalworking, and craftsmanship—the divine blacksmith who crafted weapons for the gods with unmatched precision and dedication.
+**Meet our autonomous deep worker: Hephaestus (GPT 5.2 Codex Medium). The Legitimate Craftsman Agent.**
+
+*Why "Legitimate"? When Anthropic blocked third-party access citing ToS violations, the community started joking about "legitimate" usage. Hephaestus embraces this irony—he's the craftsman who builds things the right way, methodically and thoroughly, without cutting corners.*
+
+Hephaestus is inspired by [AmpCode's deep mode](https://ampcode.com)—autonomous problem-solving with thorough research before decisive action. He doesn't need step-by-step instructions; give him a goal and he'll figure out the rest.
+
+**Key Characteristics:**
+- **Goal-Oriented**: Give him an objective, not a recipe. He determines the steps himself.
+- **Explores Before Acting**: Fires 2-5 parallel explore/librarian agents before writing a single line of code.
+- **End-to-End Completion**: Doesn't stop until the task is 100% done with evidence of verification.
+- **Pattern Matching**: Searches existing codebase to match your project's style—no AI slop.
+- **Legitimate Precision**: Crafts code like a master blacksmith—surgical, minimal, exactly what's needed.
+
 ## Installation
 
 ### For Humans