Create a roadmap for Nix

First very rough draft of a roadmap as discussed in last week's Nix team meeting.

This is merely the output of a 45mins brainstorming session so far, so absolutely nothing is settled

roadmap.md

@@ -0,0 +1,87 @@
+# Nix is everywhere and invisible
+
+Software developers use Nix as a matter of course every day, mostly without even noticing.
+Nix runs trivially, anywhere.
+
+For individuals to large organizations, Nix underpins the the entire software supply chain:
+- Developer tooling
+- Build automation
+- Binary distribution.
+
+To this end, the Nix team will work towards the following goals.
+
+## Make Nix easy to adopt
+
+  - Well-defined target user base
+  - Well-defined core user stories
+    - Ad hoc environments
+        - One-liner setup (nix-shell)
+    - Declarative environments
+        - One-liner setup ("templates")
+        - Easy modification/extension
+        - Easy and transparent usage ("direnv"/"lorri")
+    - Secret management as first-class citizen
+    - Configurations as first-class citizens
+        - Configuration/Modules/Nickel/etc.
+    - Language bindings
+    - Supply chain trust solution
+        - Content-addressed derivation
+        - Build result signing, key distribution
+        - SBOM/SLSA
+    - Unprivileged installation and use
+        <!-- valentin: this needs clarification, I still don't know what rewriting is -->
+        - Portable store?
+        - restricted-root
+        - ACLs
+        - rewriting
+    - ...
+  - Linux, MacOS and Windows support at feature parity
+
+## Make Nix a tool that users can rely on
+
+  - Reliable installer
+  - Effective testing
+    - Test coverage for all major use cases
+    - Memory safety validation (sanitizers, ...)
+    - Benchmarking infrastructure
+    - Test reports published and accessible
+  - Executable language specification
+ 
+## Make Nix a good investment for users
+
+  - Explicit compatibility guarantees (and non-guarantees)
+    - Commitment to uncompromising reproducibility
+    - Well-defined release process
+    - Feature support status
+    - Deprecation strategy
+    - LTS commitments
+    - Close Flakes schism, remove uncertanity/ambiguity/confusion
+
+  - Exemplary contributor and maintainer experience
+    - Recommended development setup
+    - Testing guidance
+    - Formalize review criteria
+    - Formalize design criteria (technical invariants)
+    - Well-defined architecture of isolated components
+        - Swappable store
+          - Formalize store protocol
+        - Swappable Nix language evaluator
+        - Swappable scheduler and remote-build system
+            - Integrate Hydra (modulo UI) into Nix
+            - Remote protocol speed and reliability improvements
+            - Binary cache protocol speed improvements
+
+    - Minimal custom code base (proven off-the-shelf components where possible)
+      - Git file hashing
+      - Sandboxing, containers
+      - Capnproto for RPC
+      - Bazel RBE protocol
+      - ...
+
+    
+<!-- roberth after meeting, feel free to remove when processed: be the binary distribution method of choice for dev tooling, such as IDE plugins that bundle their own binaries (needs Nix (libstore? installer?) to run trivially, anywhere) -->
+<!-- valentin: see the top-level goal above, does that match your idea? -->
+<!-- valentin: the architectural aspects seem to be dispersed a bit. I still think all the component notes should belong to one goal and rearranged accordingly. -->
+
+
+"Likewise, we want Nix to be everywhere. We want a world where finding a flake.nix at the root of a software project is not a pleasant surprise but something expected and common. And we want the people who design tomorrow’s software distribution mechanism to at least know and recognize the Nix model, and take that into account."