Add session discovery and template support

README.md

@@ -34,6 +34,25 @@ Pipeline config lookup for CLI commands:
   - `/usr/local/etc/narratio/pipeline.yml`
   - `/etc/narratio/pipeline.yml`
 
+Session config lookup for CLI commands:
+
+- if `--session <path>` is provided, Narratio uses that path
+- if `--session` is omitted, Narratio searches in this order:
+  - `./session.yml`
+  - `/usr/local/etc/narratio/session.yml`
+  - `/etc/narratio/session.yml`
+
+Session template support:
+
+- Narratio renders `session.yml` templates before strict YAML decode.
+- `--session-id <value>` provides the `session_id` template variable.
+- Supported placeholder forms:
+  - `{{session_id}}`
+  - `{{ session_id }}`
+- unresolved template placeholders fail with a clear error.
+- strict YAML validation still runs after rendering.
+- concrete `session.yml` files without templates remain fully supported.
+
 Optional secrets-from-files config:
 
 - `pipeline.secrets.env_dir` may point to a directory of secret files
@@ -345,6 +364,7 @@ Starter files:
 
 - `examples/pipeline.minimal.yml`
 - `examples/session.minimal.yml`
+- `examples/session.template.yml`
 - `examples/speakers.yml`
 
 ## Commands
@@ -363,6 +383,12 @@ go run ./cmd/narratio plan --session examples/session.minimal.yml
 
 Use `--config <path>` to override default pipeline lookup when needed.
 
+Run with a discoverable session template:
+
+```bash
+go run ./cmd/narratio run --session-id 2026-04-04
+```
+
 Run full pipeline:
 
 ```bash
@@ -375,6 +401,12 @@ Run analyze only:
 go run ./cmd/narratio run-stage --config examples/pipeline.minimal.yml --session examples/session.minimal.yml analyze
 ```
 
+Resume with a template session ID:
+
+```bash
+go run ./cmd/narratio resume --config examples/pipeline.minimal.yml --session examples/session.template.yml --session-id 2026-04-04
+```
+
 ## Operational Note
 
 Checksum-based stale detection is not implemented yet.