diff --git a/run.json b/run.json
index 93c27a60c..a59fc14a1 100644
--- a/run.json
+++ b/run.json
@@ -505,7 +505,7 @@
     "kind": "running"
   },
   "status_updated_at": "2026-07-09T23:18:01.698576530Z",
-  "last_event_at": "2026-07-09T23:20:54.543581444Z",
+  "last_event_at": "2026-07-09T23:23:40.959911074Z",
   "pending_control": null,
   "checkpoints": [
     {
@@ -690,9 +690,9 @@
       }
     },
     {
-      "seq": 0,
+      "seq": 49,
       "checkpoint": {
-        "timestamp": "2026-07-09T23:23:36.688531340Z",
+        "timestamp": "2026-07-09T23:23:40.538067385Z",
         "current_node": "preflight_lint",
         "completed_nodes": [
           "start",
@@ -702,24 +702,126 @@
         ],
         "node_retries": {},
         "context_values": {
-          "internal.run_id": "01KX4JRJ2NXPQASFNE8PPKTQX6",
+          "internal.work_dir": "/home/daytona/workspace/fabro",
           "failure_class": "",
-          "internal.retry_count.start": 0,
+          "internal.retry_count.preflight_lint": 0,
+          "thread.toolchain.current_node": "preflight_compile",
+          "internal.run_id": "01KX4JRJ2NXPQASFNE8PPKTQX6",
+          "internal.thread_id": "preflight_compile",
+          "outcome": "succeeded",
           "internal.retry_count.preflight_compile": 0,
-          "current_node": "preflight_lint",
+          "internal.node_visit_count": 1,
+          "command.output": "blob://sha256/12ae32cb1ec02d01eda3581b127c1fee3b0dc53572ed6baf239721a03d82e126",
+          "internal.fidelity": "compact",
+          "thread.start.current_node": "toolchain",
           "failure_signature": "",
-          "graph.rankdir": "LR",
           "graph.model_stylesheet": "\n            * { model: claude-opus-4-8; }\n        ",
           "graph.goal": "# Demote `server.integrations.slack.default_channel` to a plain literal string\n\n**Self-contained implementation plan.** Everything needed to implement this is\nin this file plus the repository. Independent — no preconditions; can land\nanytime. (It must land before a separate, later effort freezes a registry of\nconfig-field kinds, but nothing in this plan depends on that.)\n\n> **Token notation.** Interpolation tokens are written in this file without\n> their enclosing double curly braces, so the file is safe to pass directly as\n> a workflow goal (the goal templater would otherwise try to expand them).\n> Read `env.NAME`, `vars.NAME`, `secrets.NAME` as the double-curly-brace token\n> form used in the codebase, and write the real double-brace syntax in the\n> code, tests, and docs you produce.\n\n## Context and goal\n\n`server.integrations.slack.default_channel` is the last server-defined config\nfield still typed `InterpString`. Every other server-scope field was demoted\nto a plain literal under the project's rule that interpolation belongs to\nfields resolved with run context — server-startup consumption is served\nnatively by shells/compose/systemd, and a token there just ferries an env var\nacross a process boundary.\n\nThis field is exactly that case:\n\n- It was **born `Option<String>`** (2026-03-05, in the original Slack\n  integration crate; adopted into server settings 2026-04-07) and was\n  documented from the start with literal examples only. The v2 settings\n  schema typed it `InterpString` (2026-04-09) and wired env resolution the\n  same day as part of that schema's uniform staged design — not a\n  field-specific feature, and never requested or documented as interpolable.\n  The one place env-interpolated Slack channels ARE a deliberate, documented\n  feature is run-scope notification routes (added 2026-05-23) — a surface\n  this change does not touch. The uniform-staging capability was superseded\n  by the later interpolation-taxonomy decision that startup-consumed server\n  fields stay literal, under which every comparable server field was already\n  demoted.\n- It resolves **once, at server startup, env-only** — no secrets, no vars,\n  and never re-resolved at message-send time.\n- **No documentation ever advertised interpolation** on it; every doc example\n  is a plain literal channel name.\n- The **run-scope interpolating surface already exists** and is the\n  user-facing one: `run.notifications.<route>.slack.channel` and\n  `run.interviews.slack.channel` are `InterpString` with variable\n  substitution at run creation. The server field is only the zero-config\n  fallback destination for interview prompts.\n- Product direction reinforces it: in hosted deployments users have no access\n  to server env at all (their surface is variables and secrets at run scope),\n  and a future chat-integration plugin system should inherit a simple literal\n  field, not a special-case interpolating one.\n\n**Goal:** change the field to a plain `Option<String>` end-to-end, drop the\nstartup resolution, and emit the standard demoted-field warning when a\nleftover token-shaped value is found — matching how the earlier server-field\ndemotions were shipped.\n\nDesign rules (fixed):\n\n- **Keep the field** as the operator's literal fallback. Do not remove it or\n  relocate it; run scope already covers per-run needs.\n- **Wire-invisible.** `InterpString` serializes as its raw source string, so\n  the stored/wire JSON shape is unchanged by this demote. The OpenAPI schema\n  already models the field as a plain string — no spec change.\n- **Warn, don't break.** A value still containing a token-shaped span (double\n  curly braces) parses fine as a literal; emit the existing demoted-field\n  warning at resolve time so the ~3 months of nightly builds where an env\n  token would have resolved get a loud, non-fatal migration signal.\n\n## Verified current state (as of main `d5dcd1179`, 2026-07-09 — re-verify before starting; line numbers are anchors, not gospel)\n\n- Type: `lib/crates/fabro-types/src/settings/server.rs:258-271` —\n  `SlackIntegrationSettings { enabled: bool, default_channel:\n  Option<InterpString> }`.\n- Config layer: `lib/crates/fabro-config/src/layers/server.rs:237` —\n  `default_channel: Option<InterpString>`.\n- Resolve copy-through: `lib/crates/fabro-config/src/resolve/server.rs:365-369`\n  (clones the field into resolved server settings).\n- Startup resolution: `lib/crates/fabro-server/src/server.rs:2422-2430` —\n  `slack_settings.default_channel.as_ref().map(|value|\n  value.resolve(process_env_var)...)` feeding\n  `SlackService::new(bot, app, default_channel: Option<String>)`\n  (`server.rs:589-600`). The service posts interview prompts to it\n  (`server.rs:~657` `let Some(default_channel) = ... else return`, `:689`\n  `post_message`).\n- Demoted-field warning helper: `warn_if_demoted_template` in\n  `lib/crates/fabro-config/src/resolve/` (see its callers in\n  `resolve/cli.rs:50-76` for the exact usage pattern: field path string +\n  `Option<&str>` value).\n- Run-scope channels (untouched by this PR):\n  `run.notifications.<route>` slack channel and\n  `run.interviews.slack.channel`, both `InterpString`, variable-substituted at\n  run creation (`fabro-types/src/settings/run.rs`, `substitute_variables`).\n- Docs mentioning the field (all literal examples):\n  `docs/public/administration/server-configuration.mdx:453`,\n  `docs/public/human-tools/interviews.mdx:97`,\n  `docs/public/integrations/slack.mdx:112-117`.\n- OpenAPI: `docs/public/api-reference/fabro-api.yaml:13619-13623` models\n  `default_channel` as a nullable plain string in the relevant schema —\n  expected to need **no change**.\n\n## Implementation\n\n1. **Type change**: `fabro-types/src/settings/server.rs` and\n   `fabro-config/src/layers/server.rs` — `Option<InterpString>` →\n   `Option<String>`. Chase the compiler through the resolve copy-through and\n   any settings merge/serde helpers.\n2. **Demotion warning**: at the server-settings resolve site, call the\n   existing demoted-field warning helper with the field path\n   `server.integrations.slack.default_channel` and the literal value,\n   following the exact pattern of its existing callers. The warning must log\n   the field path and guidance only — never treat the value as sensitive\n   output beyond what the existing helper does.\n3. **Drop the startup resolve**: `fabro-server/src/server.rs` — pass the\n   literal through to `SlackService::new` directly; delete the\n   `resolve(process_env_var)` call and its error mapping. `SlackService`\n   itself is unchanged (it already takes `Option<String>`).\n4. **Verify (read-only) the interview routing preference**: confirm whether\n   the interview-prompt posting path prefers `run.interviews.slack.channel`\n   over the server default when both are set. If it does not, **do not build\n   routing changes** — record the finding in the PR description as a\n   follow-up observation.\n5. **Docs**: the three pages above already show literals; adjust wording only\n   if any implies interpolation (none is expected to). If the generated\n   options reference annotates the field's type, regenerate via\n   `cargo dev docs` and confirm `cargo dev docs check` is green.\n\n## Scope boundaries — deliberately NOT in this PR\n\n- **Run-scope notification and interview channel fields** — leave as-is; they\n  are the intended interpolating surface and are already correct.\n- **Slack credential resolution** (bot/app tokens via the vault at startup) —\n  leave as-is; unrelated to the channel field.\n- **Interview prompt routing behavior** — observe and report only (step 4);\n  changing which channel wins is separate product work.\n- **Any chat-integration plugin restructuring** — future work; this PR only\n  simplifies what that redesign will inherit.\n- **The config-field kind registry and its conformance tests** — separate\n  planned work; do not start it here.\n\nIf work outside these boundaries seems genuinely required for this PR to\ncompile or pass its tests, stop and state that in the PR description rather\nthan expanding scope.\n\n## Tests (failing-first; hermetic — no ambient env dependence)\n\n- A literal channel (`#releases`) parses, merges, and reaches\n  `SlackService::new` unchanged.\n- A value containing a token-shaped span parses as a **literal** (no\n  resolution, no error) and emits the demoted-field warning naming\n  `server.integrations.slack.default_channel` (log-capture, matching how the\n  existing demotion-warning tests assert).\n- Startup wiring: with the field set, the service receives exactly the\n  configured string; with it absent, `None` (existing behavior preserved).\n- Existing Slack/server integration tests pass unchanged.\n- Serde shape: a settings round-trip of the field produces the same JSON/TOML\n  as before the type change (wire-invisibility).\n\n## Acceptance / verification\n\n- `cargo +nightly-2026-04-14 fmt --check --all`\n- `cargo +nightly-2026-04-14 clippy --workspace --all-targets -- -D warnings`\n- `cargo nextest run --workspace`\n- `cargo dev docs check`\n- No OpenAPI/wire change (assert: `docs/public/api-reference/fabro-api.yaml`\n  untouched; TypeScript client regeneration not needed).\n\n## Conventions\n\n- Plain-English commit messages, PR text, and comments — describe what the\n  change does; no internal planning identifiers or plan-file names in\n  anything that ships.\n- PR description must state plainly: the field only ever resolved env vars,\n  only at server startup, and was never documented as interpolable; anyone\n  with a token in the field gets a startup warning and the value is treated\n  as a literal; per-run channels (`run.notifications`, `run.interviews.slack`)\n  remain the interpolating surface; no wire change.\n",
+          "internal.retry_count.start": 0,
+          "internal.retry_count.toolchain": 0,
+          "current_node": "preflight_lint",
+          "graph.rankdir": "LR",
+          "thread.preflight_compile.current_node": "preflight_lint"
+        },
+        "node_outcomes": {
+          "preflight_compile": {
+            "status": "succeeded",
+            "context_updates": {
+              "command.output": "blob://sha256/12ae32cb1ec02d01eda3581b127c1fee3b0dc53572ed6baf239721a03d82e126"
+            },
+            "notes": "Script completed: cargo check -q --workspace 2>&1",
+            "usage": null,
+            "timing": {
+              "wall_time_ms": 0,
+              "inference_time_ms": 0,
+              "tool_time_ms": 161483,
+              "active_time_ms": 161483
+            }
+          },
+          "preflight_lint": {
+            "status": "succeeded",
+            "context_updates": {
+              "command.output": "blob://sha256/12ae32cb1ec02d01eda3581b127c1fee3b0dc53572ed6baf239721a03d82e126"
+            },
+            "notes": "Script completed: cargo +nightly-2026-04-14 clippy -q --workspace --all-targets -- -D warnings 2>&1",
+            "usage": null,
+            "timing": {
+              "wall_time_ms": 0,
+              "inference_time_ms": 0,
+              "tool_time_ms": 162141,
+              "active_time_ms": 162141
+            }
+          },
+          "start": {
+            "status": "succeeded",
+            "usage": null
+          },
+          "toolchain": {
+            "status": "succeeded",
+            "context_updates": {
+              "command.output": "blob://sha256/20eeffec02497fbda7b51f51b06fe29c1d639551eee4d5ea9845fc1f86bd77e1"
+            },
+            "notes": "Script completed: command -v cargo >/dev/null || { curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y && sudo ln -sf $HOME/.cargo/bin/* /usr/local/bin/; }; cargo --version 2>&1",
+            "usage": null,
+            "timing": {
+              "wall_time_ms": 0,
+              "inference_time_ms": 0,
+              "tool_time_ms": 1284,
+              "active_time_ms": 1284
+            }
+          }
+        },
+        "next_node_id": "implement",
+        "git_commit_sha": "009f44f3825a82482da0edbc505a31aee18bcb3e",
+        "node_visits": {
+          "preflight_compile": 1,
+          "toolchain": 1,
+          "preflight_lint": 1,
+          "start": 1
+        }
+      },
+      "diff": {
+        "summary": {
+          "files_changed": 0,
+          "additions": 0,
+          "deletions": 0
+        }
+      }
+    },
+    {
+      "seq": 0,
+      "checkpoint": {
+        "timestamp": "2026-07-09T23:23:41.052289967Z",
+        "current_node": "implement",
+        "completed_nodes": [
+          "start",
+          "toolchain",
+          "preflight_compile",
+          "preflight_lint",
+          "implement"
+        ],
+        "node_retries": {},
+        "context_values": {
+          "internal.run_id": "01KX4JRJ2NXPQASFNE8PPKTQX6",
+          "failure_class": "deterministic",
+          "internal.retry_count.start": 0,
+          "internal.retry_count.preflight_compile": 0,
+          "current_node": "implement",
+          "failure_signature": "implement|deterministic|api_deterministic|openai|authentication",
+          "graph.rankdir": "LR",
+          "graph.model_stylesheet": "\n            * { model: claude-opus-4-8; }\n        ",
+          "thread.preflight_lint.current_node": "implement",
+          "graph.goal": "# Demote `server.integrations.slack.default_channel` to a plain literal string\n\n**Self-contained implementation plan.** Everything needed to implement this is\nin this file plus the repository. Independent — no preconditions; can land\nanytime. (It must land before a separate, later effort freezes a registry of\nconfig-field kinds, but nothing in this plan depends on that.)\n\n> **Token notation.** Interpolation tokens are written in this file without\n> their enclosing double curly braces, so the file is safe to pass directly as\n> a workflow goal (the goal templater would otherwise try to expand them).\n> Read `env.NAME`, `vars.NAME`, `secrets.NAME` as the double-curly-brace token\n> form used in the codebase, and write the real double-brace syntax in the\n> code, tests, and docs you produce.\n\n## Context and goal\n\n`server.integrations.slack.default_channel` is the last server-defined config\nfield still typed `InterpString`. Every other server-scope field was demoted\nto a plain literal under the project's rule that interpolation belongs to\nfields resolved with run context — server-startup consumption is served\nnatively by shells/compose/systemd, and a token there just ferries an env var\nacross a process boundary.\n\nThis field is exactly that case:\n\n- It was **born `Option<String>`** (2026-03-05, in the original Slack\n  integration crate; adopted into server settings 2026-04-07) and was\n  documented from the start with literal examples only. The v2 settings\n  schema typed it `InterpString` (2026-04-09) and wired env resolution the\n  same day as part of that schema's uniform staged design — not a\n  field-specific feature, and never requested or documented as interpolable.\n  The one place env-interpolated Slack channels ARE a deliberate, documented\n  feature is run-scope notification routes (added 2026-05-23) — a surface\n  this change does not touch. The uniform-staging capability was superseded\n  by the later interpolation-taxonomy decision that startup-consumed server\n  fields stay literal, under which every comparable server field was already\n  demoted.\n- It resolves **once, at server startup, env-only** — no secrets, no vars,\n  and never re-resolved at message-send time.\n- **No documentation ever advertised interpolation** on it; every doc example\n  is a plain literal channel name.\n- The **run-scope interpolating surface already exists** and is the\n  user-facing one: `run.notifications.<route>.slack.channel` and\n  `run.interviews.slack.channel` are `InterpString` with variable\n  substitution at run creation. The server field is only the zero-config\n  fallback destination for interview prompts.\n- Product direction reinforces it: in hosted deployments users have no access\n  to server env at all (their surface is variables and secrets at run scope),\n  and a future chat-integration plugin system should inherit a simple literal\n  field, not a special-case interpolating one.\n\n**Goal:** change the field to a plain `Option<String>` end-to-end, drop the\nstartup resolution, and emit the standard demoted-field warning when a\nleftover token-shaped value is found — matching how the earlier server-field\ndemotions were shipped.\n\nDesign rules (fixed):\n\n- **Keep the field** as the operator's literal fallback. Do not remove it or\n  relocate it; run scope already covers per-run needs.\n- **Wire-invisible.** `InterpString` serializes as its raw source string, so\n  the stored/wire JSON shape is unchanged by this demote. The OpenAPI schema\n  already models the field as a plain string — no spec change.\n- **Warn, don't break.** A value still containing a token-shaped span (double\n  curly braces) parses fine as a literal; emit the existing demoted-field\n  warning at resolve time so the ~3 months of nightly builds where an env\n  token would have resolved get a loud, non-fatal migration signal.\n\n## Verified current state (as of main `d5dcd1179`, 2026-07-09 — re-verify before starting; line numbers are anchors, not gospel)\n\n- Type: `lib/crates/fabro-types/src/settings/server.rs:258-271` —\n  `SlackIntegrationSettings { enabled: bool, default_channel:\n  Option<InterpString> }`.\n- Config layer: `lib/crates/fabro-config/src/layers/server.rs:237` —\n  `default_channel: Option<InterpString>`.\n- Resolve copy-through: `lib/crates/fabro-config/src/resolve/server.rs:365-369`\n  (clones the field into resolved server settings).\n- Startup resolution: `lib/crates/fabro-server/src/server.rs:2422-2430` —\n  `slack_settings.default_channel.as_ref().map(|value|\n  value.resolve(process_env_var)...)` feeding\n  `SlackService::new(bot, app, default_channel: Option<String>)`\n  (`server.rs:589-600`). The service posts interview prompts to it\n  (`server.rs:~657` `let Some(default_channel) = ... else return`, `:689`\n  `post_message`).\n- Demoted-field warning helper: `warn_if_demoted_template` in\n  `lib/crates/fabro-config/src/resolve/` (see its callers in\n  `resolve/cli.rs:50-76` for the exact usage pattern: field path string +\n  `Option<&str>` value).\n- Run-scope channels (untouched by this PR):\n  `run.notifications.<route>` slack channel and\n  `run.interviews.slack.channel`, both `InterpString`, variable-substituted at\n  run creation (`fabro-types/src/settings/run.rs`, `substitute_variables`).\n- Docs mentioning the field (all literal examples):\n  `docs/public/administration/server-configuration.mdx:453`,\n  `docs/public/human-tools/interviews.mdx:97`,\n  `docs/public/integrations/slack.mdx:112-117`.\n- OpenAPI: `docs/public/api-reference/fabro-api.yaml:13619-13623` models\n  `default_channel` as a nullable plain string in the relevant schema —\n  expected to need **no change**.\n\n## Implementation\n\n1. **Type change**: `fabro-types/src/settings/server.rs` and\n   `fabro-config/src/layers/server.rs` — `Option<InterpString>` →\n   `Option<String>`. Chase the compiler through the resolve copy-through and\n   any settings merge/serde helpers.\n2. **Demotion warning**: at the server-settings resolve site, call the\n   existing demoted-field warning helper with the field path\n   `server.integrations.slack.default_channel` and the literal value,\n   following the exact pattern of its existing callers. The warning must log\n   the field path and guidance only — never treat the value as sensitive\n   output beyond what the existing helper does.\n3. **Drop the startup resolve**: `fabro-server/src/server.rs` — pass the\n   literal through to `SlackService::new` directly; delete the\n   `resolve(process_env_var)` call and its error mapping. `SlackService`\n   itself is unchanged (it already takes `Option<String>`).\n4. **Verify (read-only) the interview routing preference**: confirm whether\n   the interview-prompt posting path prefers `run.interviews.slack.channel`\n   over the server default when both are set. If it does not, **do not build\n   routing changes** — record the finding in the PR description as a\n   follow-up observation.\n5. **Docs**: the three pages above already show literals; adjust wording only\n   if any implies interpolation (none is expected to). If the generated\n   options reference annotates the field's type, regenerate via\n   `cargo dev docs` and confirm `cargo dev docs check` is green.\n\n## Scope boundaries — deliberately NOT in this PR\n\n- **Run-scope notification and interview channel fields** — leave as-is; they\n  are the intended interpolating surface and are already correct.\n- **Slack credential resolution** (bot/app tokens via the vault at startup) —\n  leave as-is; unrelated to the channel field.\n- **Interview prompt routing behavior** — observe and report only (step 4);\n  changing which channel wins is separate product work.\n- **Any chat-integration plugin restructuring** — future work; this PR only\n  simplifies what that redesign will inherit.\n- **The config-field kind registry and its conformance tests** — separate\n  planned work; do not start it here.\n\nIf work outside these boundaries seems genuinely required for this PR to\ncompile or pass its tests, stop and state that in the PR description rather\nthan expanding scope.\n\n## Tests (failing-first; hermetic — no ambient env dependence)\n\n- A literal channel (`#releases`) parses, merges, and reaches\n  `SlackService::new` unchanged.\n- A value containing a token-shaped span parses as a **literal** (no\n  resolution, no error) and emits the demoted-field warning naming\n  `server.integrations.slack.default_channel` (log-capture, matching how the\n  existing demotion-warning tests assert).\n- Startup wiring: with the field set, the service receives exactly the\n  configured string; with it absent, `None` (existing behavior preserved).\n- Existing Slack/server integration tests pass unchanged.\n- Serde shape: a settings round-trip of the field produces the same JSON/TOML\n  as before the type change (wire-invisibility).\n\n## Acceptance / verification\n\n- `cargo +nightly-2026-04-14 fmt --check --all`\n- `cargo +nightly-2026-04-14 clippy --workspace --all-targets -- -D warnings`\n- `cargo nextest run --workspace`\n- `cargo dev docs check`\n- No OpenAPI/wire change (assert: `docs/public/api-reference/fabro-api.yaml`\n  untouched; TypeScript client regeneration not needed).\n\n## Conventions\n\n- Plain-English commit messages, PR text, and comments — describe what the\n  change does; no internal planning identifiers or plan-file names in\n  anything that ships.\n- PR description must state plainly: the field only ever resolved env vars,\n  only at server startup, and was never documented as interpolable; anyone\n  with a token in the field gets a startup warning and the value is treated\n  as a literal; per-run channels (`run.notifications`, `run.interviews.slack`)\n  remain the interpolating surface; no wire change.\n",
           "internal.fidelity": "compact",
+          "internal.retry_count.implement": 0,
           "thread.preflight_compile.current_node": "preflight_lint",
           "internal.work_dir": "/home/daytona/workspace/fabro",
-          "internal.thread_id": "preflight_compile",
+          "internal.thread_id": "preflight_lint",
           "command.output": "blob://sha256/12ae32cb1ec02d01eda3581b127c1fee3b0dc53572ed6baf239721a03d82e126",
           "internal.node_visit_count": 1,
           "thread.toolchain.current_node": "preflight_compile",
           "internal.retry_count.preflight_lint": 0,
-          "outcome": "succeeded",
+          "outcome": "failed",
           "thread.start.current_node": "toolchain",
           "internal.retry_count.toolchain": 0
         },
@@ -742,6 +844,15 @@
             "status": "succeeded",
             "usage": null
           },
+          "implement": {
+            "status": "failed",
+            "failure": {
+              "message": "LLM error: Authentication error for openai: Your authentication token has been invalidated. Please try signing in again.",
+              "category": "deterministic",
+              "signature": "api_deterministic|openai|authentication"
+            },
+            "usage": null
+          },
           "preflight_lint": {
             "status": "succeeded",
             "context_updates": {
@@ -771,11 +882,12 @@
             }
           }
         },
-        "next_node_id": "implement",
+        "next_node_id": "simplify_fable",
         "node_visits": {
           "start": 1,
           "preflight_lint": 1,
           "toolchain": 1,
+          "implement": 1,
           "preflight_compile": 1
         }
       },
@@ -894,7 +1006,12 @@
       "first_event_seq": 42,
       "prompt": null,
       "response": null,
-      "completion": null,
+      "completion": {
+        "outcome": "succeeded",
+        "notes": "Script completed: cargo +nightly-2026-04-14 clippy -q --workspace --all-targets -- -D warnings 2>&1",
+        "failure_reason": null,
+        "timestamp": "2026-07-09T23:23:36.687610316Z"
+      },
       "provider_used": null,
       "diff": null,
       "script_invocation": {
@@ -902,11 +1019,27 @@
         "command": "exec 2>&1\ncargo +nightly-2026-04-14 clippy -q --workspace --all-targets -- -D warnings 2>&1",
         "language": "shell"
       },
-      "script_timing": null,
+      "script_timing": {
+        "output": "blob://sha256/12ae32cb1ec02d01eda3581b127c1fee3b0dc53572ed6baf239721a03d82e126",
+        "exit_code": 0,
+        "duration_ms": 162141,
+        "termination": "exited",
+        "output_bytes": 0,
+        "live_streaming": false
+      },
       "parallel_results": null,
       "output": null,
+      "output_bytes": 0,
+      "live_streaming": false,
+      "termination": "exited",
       "started_at": "2026-07-09T23:20:54.543144370Z",
       "handler": "command",
+      "timing": {
+        "wall_time_ms": 162144,
+        "inference_time_ms": 0,
+        "tool_time_ms": 162141,
+        "active_time_ms": 162141
+      },
       "usage": {
         "input_tokens": 0,
         "output_tokens": 0,
@@ -915,6 +1048,181 @@
         "cache_read_tokens": 0,
         "cache_write_tokens": 0
       },
+      "state": "succeeded"
+    },
+    "implement@1": {
+      "first_event_seq": 52,
+      "prompt": null,
+      "response": null,
+      "completion": null,
+      "provider_used": {
+        "mode": "agent",
+        "provider": "openai",
+        "model": "gpt-5.5",
+        "reasoning_effort": "xhigh"
+      },
+      "diff": null,
+      "script_invocation": null,
+      "script_timing": null,
+      "parallel_results": null,
+      "output": null,
+      "started_at": "2026-07-09T23:23:40.540288281Z",
+      "handler": "agent",
+      "usage": {
+        "input_tokens": 0,
+        "output_tokens": 0,
+        "total_tokens": 0,
+        "reasoning_tokens": 0,
+        "cache_read_tokens": 0,
+        "cache_write_tokens": 0
+      },
+      "skills": {
+        "available": [
+          {
+            "name": "rust-style-guide",
+            "description": "Apply this Rust style guide when writing, reviewing, refactoring, or configuring Rust code for this project. Covers Rust 2024/MSRV, library vs application conventions, public API design, errors, panics, ownership and cloning, async/Tokio/concurrency, tracing, rustfmt/Clippy, testing with nextest, and unsafe/macro policy. Also use when setting up new Rust projects, investigating Rust performance, verifying library releases, or reviewing Rust code changes."
+          }
+        ],
+        "activated": []
+      },
+      "permission_level": "full",
+      "agent_tools": [
+        {
+          "name": "apply_patch",
+          "description": "Use the `apply_patch` tool to edit files. This is a FREEFORM tool, so do not wrap the patch in JSON.",
+          "source": {
+            "kind": "native"
+          },
+          "category": "write",
+          "invoked": false
+        },
+        {
+          "name": "close_agent",
+          "description": "Close a running subagent that is no longer needed.",
+          "source": {
+            "kind": "native"
+          },
+          "category": "subagent",
+          "invoked": false
+        },
+        {
+          "name": "glob",
+          "description": "Find files by file names using a glob pattern. Use path to choose the search root. Prefer this over shell find or ls when locating repository files.",
+          "source": {
+            "kind": "native"
+          },
+          "category": "read",
+          "invoked": false
+        },
+        {
+          "name": "grep",
+          "description": "Search file contents with a regex pattern. Use path to choose the search root, glob_filter to limit matching files, case_insensitive for case folding, and max_results to cap output.",
+          "source": {
+            "kind": "native"
+          },
+          "category": "read",
+          "invoked": false
+        },
+        {
+          "name": "read_file",
+          "description": "Read files before editing them. Returns line-numbered text and supports offset/limit for large files. Use this instead of shell cat, head, tail, or sed when inspecting repository files.",
+          "source": {
+            "kind": "native"
+          },
+          "category": "read",
+          "invoked": false
+        },
+        {
+          "name": "request_user_input",
+          "description": "Ask the human one or more questions and wait for their answers before continuing this stage.",
+          "source": {
+            "kind": "native"
+          },
+          "category": "other",
+          "invoked": false
+        },
+        {
+          "name": "send_input",
+          "description": "Send a follow-up message to a running subagent when new information or corrected instructions are needed.",
+          "source": {
+            "kind": "native"
+          },
+          "category": "subagent",
+          "invoked": false
+        },
+        {
+          "name": "shell",
+          "description": "Execute shell commands for terminal operations, package managers, tests and builds. Use dedicated tools for file reads, file edits, filename searches, and content searches. Provide timeout_ms for long-running commands.",
+          "source": {
+            "kind": "native"
+          },
+          "category": "shell",
+          "invoked": false
+        },
+        {
+          "name": "spawn_agent",
+          "description": "Spawn a subagent for independent work or context isolation. Use it for tasks that can proceed separately, and avoid duplicating the same work in the parent session.",
+          "source": {
+            "kind": "native"
+          },
+          "category": "subagent",
+          "invoked": false
+        },
+        {
+          "name": "update_plan",
+          "description": "Update the multi-step plan for the current task. Submit the entire plan; existing steps are reconciled by exact step text.",
+          "source": {
+            "kind": "native"
+          },
+          "category": "other",
+          "invoked": false
+        },
+        {
+          "name": "use_skill",
+          "description": "Load a skill's instructions by name. Call this when the user's request matches an available skill.",
+          "source": {
+            "kind": "skill"
+          },
+          "category": "other",
+          "invoked": false
+        },
+        {
+          "name": "wait",
+          "description": "Wait for a subagent to complete, then use the result to synthesize the outcome for the user.",
+          "source": {
+            "kind": "native"
+          },
+          "category": "subagent",
+          "invoked": false
+        },
+        {
+          "name": "web_fetch",
+          "description": "Fetch content from a URL that starts with http:// or https://. Pass a prompt to extract specific information or summarize the page; omit prompt to return the page content.",
+          "source": {
+            "kind": "native"
+          },
+          "category": "other",
+          "invoked": false
+        },
+        {
+          "name": "web_search",
+          "description": "Search the web using Brave Search when current external information is needed. Returns result titles, URLs, and descriptions; use web_fetch for a specific URL.",
+          "source": {
+            "kind": "native"
+          },
+          "category": "other",
+          "invoked": false
+        },
+        {
+          "name": "write_file",
+          "description": "Create new files, or overwrite an existing file only when replacement is explicitly intended. Prefer edit_file for targeted changes to existing files because write_file overwrites the full file content.",
+          "source": {
+            "kind": "native"
+          },
+          "category": "write",
+          "invoked": false
+        }
+      ],
       "state": "running"
     },
     "toolchain@1": {
diff --git a/stages/004-preflight_lint@1/output.log b/stages/004-preflight_lint@1/output.log
new file mode 100644
index 000000000..d87ba9545
--- /dev/null
+++ b/stages/004-preflight_lint@1/output.log
@@ -0,0 +1 @@
+blob://sha256/12ae32cb1ec02d01eda3581b127c1fee3b0dc53572ed6baf239721a03d82e126
\ No newline at end of file
diff --git a/stages/004-preflight_lint@1/script_timing.json b/stages/004-preflight_lint@1/script_timing.json
new file mode 100644
index 000000000..3dedcb171
--- /dev/null
+++ b/stages/004-preflight_lint@1/script_timing.json
@@ -0,0 +1,8 @@
+{
+  "output": "blob://sha256/12ae32cb1ec02d01eda3581b127c1fee3b0dc53572ed6baf239721a03d82e126",
+  "exit_code": 0,
+  "duration_ms": 162141,
+  "termination": "exited",
+  "output_bytes": 0,
+  "live_streaming": false
+}
\ No newline at end of file
diff --git a/stages/004-preflight_lint@1/status.json b/stages/004-preflight_lint@1/status.json
new file mode 100644
index 000000000..de92767ac
--- /dev/null
+++ b/stages/004-preflight_lint@1/status.json
@@ -0,0 +1,6 @@
+{
+  "outcome": "succeeded",
+  "notes": "Script completed: cargo +nightly-2026-04-14 clippy -q --workspace --all-targets -- -D warnings 2>&1",
+  "failure_reason": null,
+  "timestamp": "2026-07-09T23:23:36.687610316Z"
+}
\ No newline at end of file
diff --git a/stages/005-implement@1/prompt.md b/stages/005-implement@1/prompt.md
new file mode 100644
index 000000000..6a3eac092
--- /dev/null
+++ b/stages/005-implement@1/prompt.md
@@ -0,0 +1,194 @@
+Goal: # Demote `server.integrations.slack.default_channel` to a plain literal string
+
+**Self-contained implementation plan.** Everything needed to implement this is
+in this file plus the repository. Independent — no preconditions; can land
+anytime. (It must land before a separate, later effort freezes a registry of
+config-field kinds, but nothing in this plan depends on that.)
+
+> **Token notation.** Interpolation tokens are written in this file without
+> their enclosing double curly braces, so the file is safe to pass directly as
+> a workflow goal (the goal templater would otherwise try to expand them).
+> Read `env.NAME`, `vars.NAME`, `secrets.NAME` as the double-curly-brace token
+> form used in the codebase, and write the real double-brace syntax in the
+> code, tests, and docs you produce.
+
+## Context and goal
+
+`server.integrations.slack.default_channel` is the last server-defined config
+field still typed `InterpString`. Every other server-scope field was demoted
+to a plain literal under the project's rule that interpolation belongs to
+fields resolved with run context — server-startup consumption is served
+natively by shells/compose/systemd, and a token there just ferries an env var
+across a process boundary.
+
+This field is exactly that case:
+
+- It was **born `Option<String>`** (2026-03-05, in the original Slack
+  integration crate; adopted into server settings 2026-04-07) and was
+  documented from the start with literal examples only. The v2 settings
+  schema typed it `InterpString` (2026-04-09) and wired env resolution the
+  same day as part of that schema's uniform staged design — not a
+  field-specific feature, and never requested or documented as interpolable.
+  The one place env-interpolated Slack channels ARE a deliberate, documented
+  feature is run-scope notification routes (added 2026-05-23) — a surface
+  this change does not touch. The uniform-staging capability was superseded
+  by the later interpolation-taxonomy decision that startup-consumed server
+  fields stay literal, under which every comparable server field was already
+  demoted.
+- It resolves **once, at server startup, env-only** — no secrets, no vars,
+  and never re-resolved at message-send time.
+- **No documentation ever advertised interpolation** on it; every doc example
+  is a plain literal channel name.
+- The **run-scope interpolating surface already exists** and is the
+  user-facing one: `run.notifications.<route>.slack.channel` and
+  `run.interviews.slack.channel` are `InterpString` with variable
+  substitution at run creation. The server field is only the zero-config
+  fallback destination for interview prompts.
+- Product direction reinforces it: in hosted deployments users have no access
+  to server env at all (their surface is variables and secrets at run scope),
+  and a future chat-integration plugin system should inherit a simple literal
+  field, not a special-case interpolating one.
+
+**Goal:** change the field to a plain `Option<String>` end-to-end, drop the
+startup resolution, and emit the standard demoted-field warning when a
+leftover token-shaped value is found — matching how the earlier server-field
+demotions were shipped.
+
+Design rules (fixed):
+
+- **Keep the field** as the operator's literal fallback. Do not remove it or
+  relocate it; run scope already covers per-run needs.
+- **Wire-invisible.** `InterpString` serializes as its raw source string, so
+  the stored/wire JSON shape is unchanged by this demote. The OpenAPI schema
+  already models the field as a plain string — no spec change.
+- **Warn, don't break.** A value still containing a token-shaped span (double
+  curly braces) parses fine as a literal; emit the existing demoted-field
+  warning at resolve time so the ~3 months of nightly builds where an env
+  token would have resolved get a loud, non-fatal migration signal.
+
+## Verified current state (as of main `d5dcd1179`, 2026-07-09 — re-verify before starting; line numbers are anchors, not gospel)
+
+- Type: `lib/crates/fabro-types/src/settings/server.rs:258-271` —
+  `SlackIntegrationSettings { enabled: bool, default_channel:
+  Option<InterpString> }`.
+- Config layer: `lib/crates/fabro-config/src/layers/server.rs:237` —
+  `default_channel: Option<InterpString>`.
+- Resolve copy-through: `lib/crates/fabro-config/src/resolve/server.rs:365-369`
+  (clones the field into resolved server settings).
+- Startup resolution: `lib/crates/fabro-server/src/server.rs:2422-2430` —
+  `slack_settings.default_channel.as_ref().map(|value|
+  value.resolve(process_env_var)...)` feeding
+  `SlackService::new(bot, app, default_channel: Option<String>)`
+  (`server.rs:589-600`). The service posts interview prompts to it
+  (`server.rs:~657` `let Some(default_channel) = ... else return`, `:689`
+  `post_message`).
+- Demoted-field warning helper: `warn_if_demoted_template` in
+  `lib/crates/fabro-config/src/resolve/` (see its callers in
+  `resolve/cli.rs:50-76` for the exact usage pattern: field path string +
+  `Option<&str>` value).
+- Run-scope channels (untouched by this PR):
+  `run.notifications.<route>` slack channel and
+  `run.interviews.slack.channel`, both `InterpString`, variable-substituted at
+  run creation (`fabro-types/src/settings/run.rs`, `substitute_variables`).
+- Docs mentioning the field (all literal examples):
+  `docs/public/administration/server-configuration.mdx:453`,
+  `docs/public/human-tools/interviews.mdx:97`,
+  `docs/public/integrations/slack.mdx:112-117`.
+- OpenAPI: `docs/public/api-reference/fabro-api.yaml:13619-13623` models
+  `default_channel` as a nullable plain string in the relevant schema —
+  expected to need **no change**.
+
+## Implementation
+
+1. **Type change**: `fabro-types/src/settings/server.rs` and
+   `fabro-config/src/layers/server.rs` — `Option<InterpString>` →
+   `Option<String>`. Chase the compiler through the resolve copy-through and
+   any settings merge/serde helpers.
+2. **Demotion warning**: at the server-settings resolve site, call the
+   existing demoted-field warning helper with the field path
+   `server.integrations.slack.default_channel` and the literal value,
+   following the exact pattern of its existing callers. The warning must log
+   the field path and guidance only — never treat the value as sensitive
+   output beyond what the existing helper does.
+3. **Drop the startup resolve**: `fabro-server/src/server.rs` — pass the
+   literal through to `SlackService::new` directly; delete the
+   `resolve(process_env_var)` call and its error mapping. `SlackService`
+   itself is unchanged (it already takes `Option<String>`).
+4. **Verify (read-only) the interview routing preference**: confirm whether
+   the interview-prompt posting path prefers `run.interviews.slack.channel`
+   over the server default when both are set. If it does not, **do not build
+   routing changes** — record the finding in the PR description as a
+   follow-up observation.
+5. **Docs**: the three pages above already show literals; adjust wording only
+   if any implies interpolation (none is expected to). If the generated
+   options reference annotates the field's type, regenerate via
+   `cargo dev docs` and confirm `cargo dev docs check` is green.
+
+## Scope boundaries — deliberately NOT in this PR
+
+- **Run-scope notification and interview channel fields** — leave as-is; they
+  are the intended interpolating surface and are already correct.
+- **Slack credential resolution** (bot/app tokens via the vault at startup) —
+  leave as-is; unrelated to the channel field.
+- **Interview prompt routing behavior** — observe and report only (step 4);
+  changing which channel wins is separate product work.
+- **Any chat-integration plugin restructuring** — future work; this PR only
+  simplifies what that redesign will inherit.
+- **The config-field kind registry and its conformance tests** — separate
+  planned work; do not start it here.
+
+If work outside these boundaries seems genuinely required for this PR to
+compile or pass its tests, stop and state that in the PR description rather
+than expanding scope.
+
+## Tests (failing-first; hermetic — no ambient env dependence)
+
+- A literal channel (`#releases`) parses, merges, and reaches
+  `SlackService::new` unchanged.
+- A value containing a token-shaped span parses as a **literal** (no
+  resolution, no error) and emits the demoted-field warning naming
+  `server.integrations.slack.default_channel` (log-capture, matching how the
+  existing demotion-warning tests assert).
+- Startup wiring: with the field set, the service receives exactly the
+  configured string; with it absent, `None` (existing behavior preserved).
+- Existing Slack/server integration tests pass unchanged.
+- Serde shape: a settings round-trip of the field produces the same JSON/TOML
+  as before the type change (wire-invisibility).
+
+## Acceptance / verification
+
+- `cargo +nightly-2026-04-14 fmt --check --all`
+- `cargo +nightly-2026-04-14 clippy --workspace --all-targets -- -D warnings`
+- `cargo nextest run --workspace`
+- `cargo dev docs check`
+- No OpenAPI/wire change (assert: `docs/public/api-reference/fabro-api.yaml`
+  untouched; TypeScript client regeneration not needed).
+
+## Conventions
+
+- Plain-English commit messages, PR text, and comments — describe what the
+  change does; no internal planning identifiers or plan-file names in
+  anything that ships.
+- PR description must state plainly: the field only ever resolved env vars,
+  only at server startup, and was never documented as interpolable; anyone
+  with a token in the field gets a startup warning and the value is treated
+  as a literal; per-run channels (`run.notifications`, `run.interviews.slack`)
+  remain the interpolating surface; no wire change.
+
+
+## Completed stages
+- **toolchain**: succeeded
+  - Script: `command -v cargo >/dev/null || { curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y && sudo ln -sf $HOME/.cargo/bin/* /usr/local/bin/; }; cargo --version 2>&1`
+  - Output:
+    ```
+    cargo 1.96.0 (30a34c682 2026-05-25)
+    ```
+- **preflight_compile**: succeeded
+  - Script: `cargo check -q --workspace 2>&1`
+  - Output: (empty)
+- **preflight_lint**: succeeded
+  - Script: `cargo +nightly-2026-04-14 clippy -q --workspace --all-targets -- -D warnings 2>&1`
+  - Output: (empty)
+
+
+Read the plan file referenced in the goal and implement every step. Make all the code changes described in the plan. Use red/green TDD. Be sure to use the rust-style-guide skill to help you follow this repo's Rust style conventions.
\ No newline at end of file
diff --git a/stages/005-implement@1/provider_used.json b/stages/005-implement@1/provider_used.json
new file mode 100644
index 000000000..c57772db6
--- /dev/null
+++ b/stages/005-implement@1/provider_used.json
@@ -0,0 +1,6 @@
+{
+  "mode": "agent",
+  "provider": "openai",
+  "model": "gpt-5.5",
+  "reasoning_effort": "xhigh"
+}
\ No newline at end of file