## Summary
This PR makes agent execution a strict two-backend contract: API-backed
stages use Fabro-owned model/provider auth, while ACP-backed stages
launch a user-supplied stdio process that owns its own auth and tools.
That removes the legacy CLI backend and prevents ACP execution from
accidentally resolving or forwarding provider credentials.
## Changes
- Replaces the old `api`/`cli`/`acp` backend model with `AgentBackend {
api, acp }`, with `backend=\"cli\"` rejected and migrated toward
explicit ACP process configuration.
- Splits ACP process configuration into `acp.command` for shell command
strings and `acp.config` for JSON stdio configs, while rejecting legacy
`acp_command`.
- Restricts ACP to `agent` nodes and rejects API-only attributes such as
`model`, `provider`, `reasoning_effort`, `max_tokens`, and `speed` on
ACP nodes.
- Deletes the workflow CLI runtime, CLI credential resolver surface, CLI
live smoke tests, and `agent.cli.*` event handling.
- Updates ACP events and projections to report process identity
(`command`, optional `config_name`) rather than provider/model metadata.
- Updates import/stylesheet propagation, CLI workflow smoke coverage,
server steering tests, and web model extraction for the new
event/backend contract.
## Validation
- `cargo check -p fabro-auth -p fabro-acp -p fabro-workflow -p fabro-cli
--all-targets`
- `cargo nextest run -p fabro-auth -p fabro-acp -p fabro-validate -p
fabro-store -p fabro-workflow --lib`
- `cargo nextest run -p fabro-acp`
- `cargo nextest run -p fabro-cli --test it
workflow::acp::acp_backend_workflow`
- `cargo nextest run -p fabro-workflow --test it
codergen_without_backend_simulated`
- `cargo nextest run -p fabro-workflow --test it
import_e2e_through_engine`
- `cargo nextest run -p fabro-workflow --test it stylesheet_application`
- `cargo nextest run -p fabro-server
steer_with_active_acp_stage_returns_non_steerable_conflict`
- `cargo nextest run -p fabro-server
active_acp_stage_marker_clears_on_terminal_paths`
- `cargo nextest run -p fabro-types
agent_backend_accepts_only_api_and_acp`
- `cd apps/fabro-web && bun test app/routes/run-stages.test.ts`
- `cd apps/fabro-web && bun run typecheck`
- `cargo +nightly-2026-04-14 fmt --check --all`
- `cargo +nightly-2026-04-14 clippy --workspace --all-targets -- -D
warnings`
---
[](https://github.com/EveryInc/compound-engineering-plugin)
🤖 Generated with GPT-5 via [Codex](https://openai.com/codex)
---------
Co-authored-by: Peter Bell <4843+PeterBell@users.noreply.github.com>
## Summary
`fabro validate` had inconsistent behavior for undefined template
variables depending on whether the prompt was inline or loaded via an
`@file` reference. Inline `{{ inputs.foo }}` produced a warning and
validation passed; the same expression inside a `@file`-imported prompt
produced a hard validation error.
Fixes#286.
## Root cause
Two template-rendering passes with different strictness, applied to
disjoint inputs:
1. **DOT-source pass**
(`lib/crates/fabro-workflow/src/operations/create.rs`) honored
`RenderMode::Structural` for `fabro validate` — undefined variables
downgraded to a `Severity::Warning` diagnostic, then lenient render
finished the job.
2. **Per-attribute pass**
(`lib/crates/fabro-workflow/src/transforms/variable_expansion.rs`)
inside `TemplateTransform` was always strict and had no `RenderMode`
awareness. Because `FileInliningTransform` runs *before*
`TemplateTransform`, expressions inside `@file` content only ever
encountered the strict pass.
## Fix
- Plumb `RenderMode` through `TransformOptions` into
`TemplateTransform`.
- In `RenderMode::Structural`, the transform catches
`TemplateError::UndefinedVariable` per attribute, emits a warning
diagnostic, and falls back to `render_lenient`.
- Diagnostics flow through a new `Transformed.diagnostics` field into
`Validated` alongside lint output.
- Diagnostics now include `node_id` when the undefined variable was
found inside a node attribute, which is more useful than the previous
"at line 1" location.
- `RenderMode` and the shared `template_undefined_variable_diagnostic`
helper moved to `pipeline/types.rs` so the transform layer can reach
them without a circular dep.
Strict mode (`fabro run`, preflight) is unchanged — undefined inputs
still hard-fail before a run is created.
## Behavior
Illustrative output shapes (variable names and line numbers depend on
the fixture):
Inline prompt (unchanged):
```
warning: undefined template variable `inputs.<name>` at line <n> (template_undefined_variable)
Validation: OK
```
`@file`-imported prompt (previously a hard error, now matches inline —
node-attributed instead of line-attributed):
```
warning [node: <id>]: undefined template variable `inputs.<name>` in node `<id>` (template_undefined_variable)
Validation: OK
```
## Test plan
- [x] `cargo nextest run --workspace` — 5773/5773 passing
- [x] `cargo +nightly-2026-04-14 clippy --workspace --all-targets -- -D
warnings` clean
- [x] `cargo +nightly-2026-04-14 fmt --check --all` clean
- [x] New regression test
`bare_fabro_with_unbound_inputs_in_imported_prompt_validates_structurally_with_warning`
in `lib/crates/fabro-cli/tests/it/cmd/validate.rs` against new fixture
`test/templated_unbound_imported/`
- [x] Existing
`bare_fabro_with_unbound_inputs_validates_structurally_with_warning` and
`strict_render_hard_fails_on_unbound_inputs` still pass — verifies
inline structural and run-start strict behavior are both preserved
- [x] Manual reproduction of the exact inputs from the issue now
succeeds with a warning
🤖 Generated with [Claude Code](https://claude.com/claude-code)
---------
Co-authored-by: Aleksi Asikainen <1086393+salieri@users.noreply.github.com>
Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Adds a Defining Workflows page covering the import placeholder
syntax, node ID prefixing, the imported-file contract, default
attribute and class propagation, retry_target remapping, templating
behavior, nested imports, empty-import bypass, and the import_error
validation surface.
## Summary
Implemented ACP support as a first-class Fabro backend alongside `api`
and `cli`. This adds a new `fabro-acp` crate using the official ACP Rust
crates, routes `backend=\"acp\"` for agent and prompt nodes, adds
sandbox stdio support for local/Docker/test-support paths, emits ACP
workflow events/projections, updates server steerability handling,
validation, documentation, and black-box CLI coverage.
## Test Plan
Passed strict non-live verification:
- `ulimit -n 4096 && cargo nextest run -p fabro-workflow --run-ignored
all --no-fail-fast` — 1162 passed, 0 skipped.
- `ulimit -n 4096 && cargo nextest run -p fabro-acp -p fabro-sandbox -p
fabro-workflow -p fabro-validate -p fabro-store -p fabro-server -p
fabro-cli --run-ignored all --no-fail-fast -E 'not
test(daytona_streaming_live_smoke)'` — 3125 passed.
- `cargo build --workspace` — passed.
- `ulimit -n 4096 && cargo nextest run --workspace --run-ignored all
--no-fail-fast -E 'not test(daytona_streaming_live_smoke)'` — 5666
passed.
- `cargo +nightly-2026-04-14 fmt --check --all` — passed.
- `cargo +nightly-2026-04-14 clippy --workspace --all-targets -- -D
warnings` — passed.
Live-environment tests skipped/excluded under explicit user override:
- `daytona_streaming_live_smoke` was excluded from final nextest runs
because it requires live Daytona infrastructure and `DAYTONA_API_KEY`.
- Confirmed with `env -u DAYTONA_API_KEY cargo test -p fabro-sandbox
--features daytona --test daytona_streaming_live
daytona_streaming_live::daytona_streaming_live_smoke -- --ignored
--exact --nocapture`: failed fast with `DAYTONA_API_KEY must be set to
run this live smoke test`.
Add a progressive human interview workflow and teach human gates to honor explicit question_type values so the workflow can exercise yes/no, confirmation, multiple-choice, multi-select, and freeform prompts before summarizing the answers.
Invert the docs convention so the Mintlify-published site lives under
docs/public/ and internal artifacts (strategy docs, brainstorms, plans,
etc.) sit at docs/ root or docs/internal/. Tools that default to writing
into docs/ now land in the catch-all instead of leaking into the
published tree.
- Move Mintlify content (administration/, agents/, api-reference/,
changelog/, core-concepts/, examples/, execution/, getting-started/,
human-tools/, integrations/, languages/, reference/, tutorials/,
workflows/, images/, logo/, docs.json, favicon.svg, dot-highlight.js)
into docs/public/.
- Collapse docs-internal/ into docs/internal/.
- Update Rust path references (fabro-api/build.rs, fabro-server,
fabro-dev), TypeScript generator arg, CI path filters, clippy.toml
reasons, AGENTS.md/CLAUDE.md, and README.md image refs.
Mintlify dashboard project root must be updated to docs/public/ in a
follow-up. .mintignore move/trim and .claude/skills/ updates land in a
separate commit.
