diff --git a/.github/workflows/doctor-loop.yml b/.github/workflows/doctor-loop.yml
new file mode 100644
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+++ b/.github/workflows/doctor-loop.yml
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+name: doctor-loop
+
+# Layer-2 autonomous Railway fleet doctor for trios-trainer-igla.
+# Bypass-discipline: lives in its own workflow + crate, does NOT modify
+# gardener-loop.yml (v2.9 / PR #149 territory). Skill: docker-railway-doctor v1.2.
+# Anchor: phi^2 + phi^-2 = 3 · TRINITY · NEVER STOP · DOI 10.5281/zenodo.19227877
+
+on:
+  schedule:
+    - cron: '*/5 * * * *'  # every 5 minutes (cron-tier monitor runs hourly)
+  workflow_dispatch:
+    inputs:
+      action:
+        description: 'doctor action: diagnose | cure | cure-all'
+        required: false
+        default: 'diagnose'
+
+concurrency:
+  group: doctor-loop
+  cancel-in-progress: false
+
+permissions:
+  contents: read
+  actions: write
+  issues: write
+
+jobs:
+  doctor:
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+    steps:
+      - name: Skeleton — Layer-2 doctor stub (PR #155, feat/doctor-v1.0)
+        run: |
+          echo "DOCTOR Layer-2 skeleton — not yet wired."
+          echo "Anchor: phi^2 + phi^-2 = 3"
+          echo "Action: ${{ inputs.action || 'diagnose' }}"
+          echo "Pending merge of crates/tri-doctor (PR #155)."
+          # TODO: invoke `cargo run -p tri-doctor -- $ACTION` once the crate lands.
+          # TODO: append row to public.gardener_runs with action='doctor_cure'.
+          # TODO: emit Railway serviceInstanceDeployV2 force-redeploys on AMBER.
diff --git a/crates/tri-doctor/Cargo.toml b/crates/tri-doctor/Cargo.toml
new file mode 100644
index 00000000..c3de14b2
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+++ b/crates/tri-doctor/Cargo.toml
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+[package]
+name = "tri-doctor"
+version = "0.1.0"
+edition = "2021"
+license = "Apache-2.0"
+description = "Layer-1 autonomous Railway fleet doctor for trios-trainer-igla. Skill: docker-railway-doctor v1.2."
+
+[[bin]]
+name = "tri-doctor"
+path = "src/main.rs"
+
+[dependencies]
+anyhow = "1"
+clap = { version = "4", features = ["derive"] }
+serde = { version = "1", features = ["derive"] }
+serde_json = "1"
+sqlx = { version = "0.7", features = ["runtime-tokio-rustls", "postgres", "chrono"] }
+tokio = { version = "1", features = ["full"] }
+reqwest = { version = "0.12", features = ["json", "rustls-tls"], default-features = false }
+chrono = { version = "0.4", features = ["serde"] }
diff --git a/crates/tri-doctor/src/main.rs b/crates/tri-doctor/src/main.rs
new file mode 100644
index 00000000..649adaab
--- /dev/null
+++ b/crates/tri-doctor/src/main.rs
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+// tri-doctor — Layer-1 autonomous Railway fleet doctor.
+// Anchor: phi^2 + phi^-2 = 3 · TRINITY · NEVER STOP · DOI 10.5281/zenodo.19227877
+//
+// Skill: docker-railway-doctor v1.2 (Perplexity Computer user-scope).
+// This is a skeleton stub — actual cure logic lands in a follow-up PR.
+
+use anyhow::Result;
+use clap::{Parser, Subcommand};
+
+#[derive(Parser, Debug)]
+#[command(name = "tri-doctor", version, about = "Autonomous Railway fleet doctor")]
+struct Cli {
+    #[command(subcommand)]
+    command: Cmd,
+}
+
+#[derive(Subcommand, Debug)]
+enum Cmd {
+    /// Run R5-honest probes (writer pulse, bit-id, seq-burn, matrix champ) and emit JSON verdict.
+    Diagnose,
+    /// Apply a single cure-action: force-redeploy + variable upsert + GARDENER_LIVE flap.
+    Cure,
+    /// Apply all cure-actions in sequence (max 40 per Railway GraphQL quota).
+    CureAll,
+}
+
+#[tokio::main]
+async fn main() -> Result<()> {
+    let cli = Cli::parse();
+    match cli.command {
+        Cmd::Diagnose => {
+            println!("{{\"verdict\":\"AMBER\",\"reason\":\"skeleton-stub\",\"anchor\":\"phi^2+phi^-2=3\"}}");
+        }
+        Cmd::Cure => {
+            anyhow::bail!("cure not yet implemented — pending Layer-1 wiring");
+        }
+        Cmd::CureAll => {
+            anyhow::bail!("cure-all not yet implemented — pending Layer-1 wiring");
+        }
+    }
+    Ok(())
+}