Initial commit HEAD main

19 files changed, 2313 insertions, 0 deletions

diff --git a/.dir-locals.el b/.dir-locals.el
new file mode 100644
index 0000000..834b37f
--- /dev/null
+++ b/.dir-locals.el
@@ -0,0 +1,13 @@
+;;; Directory Local Variables
+;;; For more information see (info "(emacs) Directory Variables")
+
+((nil
+  (indent-tabs-mode))
+ (makefile-gmake-mode
+  (indent-tabs-mode t))
+ (scheme-mode
+  (fill-column . 80)
+  ;; TODO: Font lock define-record-type* and
+  ;; define-public-record-type* correctly.
+  (eval . (put 'call-with-container* 'scheme-indent-function 2))
+  (eval . (put 'call-with-input-pipe 'scheme-indent-function 1))))
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..f7978e2
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+*.go
+.nrepl-port
+kaakaa/config.scm
\ No newline at end of file
diff --git a/.guix/kaakaa-package.scm b/.guix/kaakaa-package.scm
new file mode 100644
index 0000000..f3f0136
--- /dev/null
+++ b/.guix/kaakaa-package.scm
@@ -0,0 +1,94 @@
+;;; kaakaa --- Tiny, security-focused AI agent in Guile
+;;; Copyright © 2026 Arun Isaac <arunisaac@systemreboot.net>
+;;;
+;;; This file is part of kaakaa.
+;;;
+;;; kaakaa is free software: you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation, either version 3 of the License, or
+;;; (at your option) any later version.
+;;;
+;;; kaakaa is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+;;; General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with kaakaa.  If not, see <https://www.gnu.org/licenses/>.
+
+(define-module (kaakaa-package)
+  #:use-module ((gnu packages guile)
+                #:select (guile-3.0 guile-json-4))
+  #:use-module ((gnu packages guile-xyz)
+                #:select (guile-lens guile-run64))
+  #:use-module ((gnu packages package-management)
+                #:select (guix))
+  #:use-module (guix build-system gnu)
+  #:use-module (guix gexp)
+  #:use-module (guix git-download)
+  #:use-module ((guix licenses) #:prefix license:)
+  #:use-module (guix packages)
+  #:use-module (guix utils))
+
+(define-public kaakaa
+  (package
+    (name "kaakaa")
+    (version "0.1.0")
+    (source (local-file ".."
+                        "kaakaa-checkout"
+                        #:recursive? #t
+                        #:select? (or (git-predicate (dirname (current-source-directory)))
+                                      (const #t))))
+    (build-system gnu-build-system)
+    (arguments
+     (list #:make-flags
+           #~(list (string-append "prefix=" #$output))
+           #:modules `(((guix build guile-build-system)
+                        #:select (target-guile-effective-version))
+                       ,@%default-gnu-imported-modules)
+           #:phases
+           (with-imported-modules `((guix build guile-build-system)
+                                    ,@%default-gnu-imported-modules)
+             #~(modify-phases %standard-phases
+                 (replace 'patch-source-shebangs
+                   (lambda* (#:key inputs #:allow-other-keys)
+                     (substitute* "bin/kaakaa"
+                       (("^exec guile")
+                        (string-append "exec "
+                                       (search-input-file inputs "/bin/guile"))))))
+                 (delete 'configure)
+                 (add-after 'install 'wrap
+                   (lambda* (#:key inputs outputs #:allow-other-keys)
+                     (let ((out (assoc-ref outputs "out"))
+                           (effective-version (target-guile-effective-version)))
+                       (wrap-program (string-append out "/bin/kaakaa")
+                         `("GUILE_LOAD_PATH" prefix
+                           (,(string-append out "/share/guile/site/" effective-version)
+                            ,(getenv "GUILE_LOAD_PATH")))
+                         `("GUILE_LOAD_COMPILED_PATH" prefix
+                           (,(string-append out "/lib/guile/"
+                                            effective-version "/site-ccache")
+                            ,(getenv "GUILE_LOAD_COMPILED_PATH")))))))))))
+    (inputs
+     (list guile-3.0 guile-json-4 guile-lens guix))
+    (native-inputs
+     (list guile-run64))
+    (home-page "https://forge.systemreboot.net/kaakaa")
+    (synopsis "Tiny, security-focused AI agent in Guile")
+    (description
+     "kaakaa is a tiny, security-focused AI agent written in Guile with
+minimal dependencies. Kaakaa works with any LLM that provides an
+OpenAI-compatible API.
+
+kaakaa runs tool calls securely using containers and capability-based
+access. Tool calls have limited or no access to the filesystem and to
+the network. Capabilities allow network access to be controlled with
+fine granularity. Containers are implemented using Guix's container
+API.
+
+kaakaa offers no user interface on its own. Instead, it speaks
+the @acronym{ACP, Agent Client Protocol} and allows you to use any
+compatible user interface of your choice.")
+    (license license:gpl3+)))
+
+kaakaa
diff --git a/COPYING b/COPYING
new file mode 100644
index 0000000..f288702
--- /dev/null
+++ b/COPYING
@@ -0,0 +1,674 @@
+                    GNU GENERAL PUBLIC LICENSE
+                       Version 3, 29 June 2007
+
+ Copyright (C) 2007 Free Software Foundation, Inc. <https://fsf.org/>
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
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+GNU General Public License for most of our software; it applies also to
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+available, or (2) arrange to deprive yourself of the benefit of the
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+
+  If, pursuant to or in connection with a single transaction or
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+
+  A patent license is "discriminatory" if it does not include within
+the scope of its coverage, prohibits the exercise of, or is
+conditioned on the non-exercise of one or more of the rights that are
+specifically granted under this License.  You may not convey a covered
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+contain the covered work, unless you entered into that arrangement,
+or that patent license was granted, prior to 28 March 2007.
+
+  Nothing in this License shall be construed as excluding or limiting
+any implied license or other defenses to infringement that may
+otherwise be available to you under applicable patent law.
+
+  12. No Surrender of Others' Freedom.
+
+  If conditions are imposed on you (whether by court order, agreement or
+otherwise) that contradict the conditions of this License, they do not
+excuse you from the conditions of this License.  If you cannot convey a
+covered work so as to satisfy simultaneously your obligations under this
+License and any other pertinent obligations, then as a consequence you may
+not convey it at all.  For example, if you agree to terms that obligate you
+to collect a royalty for further conveying from those to whom you convey
+the Program, the only way you could satisfy both those terms and this
+License would be to refrain entirely from conveying the Program.
+
+  13. Use with the GNU Affero General Public License.
+
+  Notwithstanding any other provision of this License, you have
+permission to link or combine any covered work with a work licensed
+under version 3 of the GNU Affero General Public License into a single
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+
+  14. Revised Versions of this License.
+
+  The Free Software Foundation may publish revised and/or new versions of
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+be similar in spirit to the present version, but may differ in detail to
+address new problems or concerns.
+
+  Each version is given a distinguishing version number.  If the
+Program specifies that a certain numbered version of the GNU General
+Public License "or any later version" applies to it, you have the
+option of following the terms and conditions either of that numbered
+version or of any later version published by the Free Software
+Foundation.  If the Program does not specify a version number of the
+GNU General Public License, you may choose any version ever published
+by the Free Software Foundation.
+
+  If the Program specifies that a proxy can decide which future
+versions of the GNU General Public License can be used, that proxy's
+public statement of acceptance of a version permanently authorizes you
+to choose that version for the Program.
+
+  Later license versions may give you additional or different
+permissions.  However, no additional obligations are imposed on any
+author or copyright holder as a result of your choosing to follow a
+later version.
+
+  15. Disclaimer of Warranty.
+
+  THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
+APPLICABLE LAW.  EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
+HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY
+OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO,
+THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+PURPOSE.  THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM
+IS WITH YOU.  SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF
+ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
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+  16. Limitation of Liability.
+
+  IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
+THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
+GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
+USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
+DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
+PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
+EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGES.
+
+  17. Interpretation of Sections 15 and 16.
+
+  If the disclaimer of warranty and limitation of liability provided
+above cannot be given local legal effect according to their terms,
+reviewing courts shall apply local law that most closely approximates
+an absolute waiver of all civil liability in connection with the
+Program, unless a warranty or assumption of liability accompanies a
+copy of the Program in return for a fee.
+
+                     END OF TERMS AND CONDITIONS
+
+            How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+state the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+Also add information on how to contact you by electronic and paper mail.
+
+  If the program does terminal interaction, make it output a short
+notice like this when it starts in an interactive mode:
+
+    <program>  Copyright (C) <year>  <name of author>
+    This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+    This is free software, and you are welcome to redistribute it
+    under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License.  Of course, your program's commands
+might be different; for a GUI interface, you would use an "about box".
+
+  You should also get your employer (if you work as a programmer) or school,
+if any, to sign a "copyright disclaimer" for the program, if necessary.
+For more information on this, and how to apply and follow the GNU GPL, see
+<https://www.gnu.org/licenses/>.
+
+  The GNU General Public License does not permit incorporating your program
+into proprietary programs.  If your program is a subroutine library, you
+may consider it more useful to permit linking proprietary applications with
+the library.  If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.  But first, please read
+<https://www.gnu.org/licenses/why-not-lgpl.html>.
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..39d49a2
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,94 @@
+# kaakaa --- Tiny, security-focused AI agent in Guile
+# Copyright © 2026 Arun Isaac <arunisaac@systemreboot.net>
+#
+# This file is part of kaakaa.
+#
+# kaakaa is free software: you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# kaakaa is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with kaakaa.  If not, see <https://www.gnu.org/licenses/>.
+
+project = kaakaa
+version = 0.1.0
+
+GIT = git
+GPG = gpg
+GUILD = guild
+GUILE = guile
+GUILE_RUN64 = guile-run64
+LZIP = lzip
+SED = sed
+
+prefix ?= /usr/local
+bindir ?= $(prefix)/bin
+datarootdir ?= $(prefix)/share
+libdir ?= $(prefix)/lib
+
+guile_effective_version = 3.0
+
+top_level_module_dir = $(project)
+config_file = $(top_level_module_dir)/config.scm
+config_file_template = $(config_file).in
+sources = $(filter-out $(config_file), \
+                       $(wildcard $(top_level_module_dir)/*.scm) \
+                       $(wildcard $(top_level_module_dir)/tools/*.scm))
+objects = $(sources:.scm=.go) $(config_file:.scm=.go)
+scripts = $(wildcard bin/*)
+tests = $(wildcard tests/*.scm)
+distribute_files = $(sources) $(config_file_template) $(scripts) \
+                   $(tests) pre-inst-env guix.scm \
+                   .guix/kaakaa-package.scm Makefile \
+                   COPYING README.md
+
+scmdir = $(datarootdir)/guile/site/$(guile_effective_version)
+godir = $(libdir)/guile/$(guile_effective_version)/site-ccache
+
+.PHONY: all clean install ares
+
+all: $(objects) $(config_file)
+
+%.scm: %.scm.in
+	$(SED) -e 's|@PROJECT@|$(project)|' -e 's|@VERSION@|$(version)|' $< > $@
+
+%.go: %.scm $(config_file)
+	GUILE_AUTO_COMPILE=0 $(GUILD) compile -L . -o $@ $<
+
+check:
+	./pre-inst-env $(GUILE_RUN64) $(tests)
+
+install: $(sources) $(config_file) $(objects) $(scripts)
+	install -D $(scripts) --target-directory $(bindir)
+	for source in $(sources) $(config_file); do \
+		install -D $$source $(scmdir)/$$source; \
+	done
+	for object in $(objects); do \
+		install -D $$object $(godir)/$$object; \
+	done
+
+# Build distribution tarball
+
+dist_archive = $(project)-$(version).tar.lz
+
+dist: $(dist_archive)
+distsign: $(dist_archive).asc
+
+$(dist_archive): .git/refs/heads/main
+	$(GIT) archive --prefix $(basename $(basename $@))/ --format=tar main $(distribute_files) \
+		| $(LZIP) --force --output $@
+
+%.asc: %
+	$(GPG) --detach-sign --armor $<
+
+clean:
+	rm -f $(objects) $(config_file)
+
+ares:
+	./pre-inst-env $(GUILE) -c '(begin ((@ (ares server) run-nrepl-server)))'
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..cda6c09
--- /dev/null
+++ b/README.md
@@ -0,0 +1,25 @@
+kaakaa (pronounced kah-kah) is a tiny, security-focused AI agent written in Guile with minimal dependencies. Kaakaa works with any LLM that provides an OpenAI-compatible API.
+
+kaakaa runs tool calls securely using containers and capability-based access. Tool calls have limited or no access to the filesystem and to the network. Capabilities allow network access to be controlled with fine granularity. Containers are implemented using Guix's container API.
+
+Kaakaa offers no user interface on its own. Instead, it speaks the [Agent Client Protocol (ACP)](https://agentclientprotocol.com/) and allows you to use any compatible user interface of your choice.
+
+# Author's note on AI use
+
+This program is not an endorsement of AI or its use. Please think for yourself, and use AI wisely (if at all). The societal, environmental and ethical consequences of AI are real, and I struggle with them myself. I hope we, as the free software community, can come to some reasonable consensus on how we are going to deal with AI. Meanwhile, I have been [nerd sniped](https://xkcd.com/356/) into experimenting with AI, and this is my effort to disentangle myself from popular AI agents that are recklessly biased towards convenience and thoughtless about dependencies (think npm crap).
+
+Here are my current views on the topic. I fully retain the right to change my views on this later, of course.
+
+As a Schemer, I believe that programs must be written for people to read, and only incidentally for machines to execute (from the Preface to SICP). But, I don't particularly care if program authors use AI as a writing/coding/debugging aid, as long as they still subscribe to *high* standards of readability. Large chunks of poorly vetted AI slop are unfair on the reader and are therefore unacceptable. Vibe coding is not a substitute for human skill, but I'm afraid a lot of people are going to think so.
+
+## AI use in this project
+
+Despite being an AI agent, all code in this project is lovingly hand-crafted. I wouldn't leave security to a stochastic machine like an LLM. And of course, readability and the craft are important ideals. In the future, I may get AI to generate boring things like examples and test cases, but that's about it.
+
+# License
+
+kaakaa is free software released under the terms of the [GNU General Public License](https://www.gnu.org/licenses/gpl.html), either version 3 of the License, or (at your option) any later version.
+
+# The Name
+
+kaakaa (காக்கா—pronounced kah-kah) means "crow" 🐦‍⬛ in Tamil. It also evokes "kaaka" (காக்க—pronounced kah-kuh), meaning "to protect". Crows are intelligent birds, and kaakaa protects you from reckless/malicious tool use by LLMs.
diff --git a/bin/kaakaa b/bin/kaakaa
new file mode 100755
index 0000000..5f94176
--- /dev/null
+++ b/bin/kaakaa
@@ -0,0 +1,109 @@
+#!/usr/bin/env sh
+# -*- mode: scheme; -*-
+exec guile --no-auto-compile -e main -s "$0" "$@"
+!#
+;;; kaakaa --- Tiny, security-focused AI agent in Guile
+;;; Copyright © 2026 Arun Isaac <arunisaac@systemreboot.net>
+;;;
+;;; This file is part of kaakaa.
+;;;
+;;; kaakaa is free software: you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation, either version 3 of the License, or
+;;; (at your option) any later version.
+;;;
+;;; kaakaa is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+;;; General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with kaakaa.  If not, see <https://www.gnu.org/licenses/>.
+
+(use-modules (rnrs io ports)
+             (srfi srfi-37)
+             (ice-9 match)
+             (kaakaa config)
+             (kaakaa openai)
+             (kaakaa tea)
+             (kaakaa tools base)
+             (kaakaa utils))
+
+(define (invalid-option opt name arg result)
+  (error "Invalid option" name))
+
+(define (invalid-argument arg result)
+  (error "Invalid argument" arg))
+
+(define %options
+  (list (option (list #\m "model") #t #f
+                (lambda (opt name arg result)
+                  (acons 'model arg
+                         result)))
+        (option (list #\a "api-base-uri") #t #f
+                (lambda (opt name arg result)
+                  (acons 'api-base-uri arg result)))
+        (option (list #\k "api-key-command") #t #f
+                (lambda (opt name arg result)
+                  (acons 'api-key-command arg result)))
+        (option (list #\v "version") #f #f
+                (lambda (opt name arg result)
+                  (acons 'version #t result)))
+        (option (list #\h "help") #f #f
+                (lambda (opt name arg result)
+                  (acons 'help #t result)))))
+
+(define (print-usage program)
+  "Print kaakaa usage. @var{program} is the name of the executable used
+to invoke kaakaa."
+  (format (current-error-port)
+          "Usage: ~a [OPTIONS]
+Run kaakaa AI agent.
+
+  --api-base-uri=URI             base API URI of LLM provider
+  --api-key-command=COMMAND      command to run to get API key
+  --model=MODEL                  LLM model name
+
+  --version                      print version and exit
+  --help                         print this help and exit
+"
+          program))
+
+(define (die fmt . args)
+  "Print formatted message, followed by a newline and exit with failure."
+  (apply format (current-error-port) fmt args)
+  (newline (current-error-port))
+  (exit #f))
+
+(define (get-api-key api-key-command)
+  "Run @var{api-key-command} and get the API key."
+  ;; We use a shell to execute since
+  ;; 1. api-key-command is a string, not a list of string arguments
+  ;; 2. api-key-command may contain pipes
+  (call-with-input-pipe `("sh" "-c" ,api-key-command)
+    get-string-all))
+
+(define main
+  (match-lambda
+    ((program args ...)
+     (let ((args (args-fold args
+                            %options
+                            invalid-option
+                            invalid-argument
+                            '((model . "anthropic/claude-opus-4.6")
+                              (api-base-uri . "https://openrouter.ai")))))
+       (when (assq-ref args 'help)
+         (print-usage program)
+         (exit #t))
+       (when (assq-ref args 'version)
+         (format (current-output-port)
+                 "~a ~a~%"
+                 %project %version)
+         (exit #t))
+       (unless (assq-ref args 'api-key-command)
+         (die "--api-key-command not specified"))
+       (tea-loop (initial-state)
+                 (assq-ref args 'api-base-uri)
+                 (get-api-key (assq-ref args 'api-key-command))
+                 (assq-ref args 'model)
+                 %base-tools)))))
diff --git a/guix.scm b/guix.scm
new file mode 120000
index 0000000..f9a22d9
--- /dev/null
+++ b/guix.scm
@@ -0,0 +1 @@
+.guix/kaakaa-package.scm
\ No newline at end of file
diff --git a/kaakaa/config.scm.in b/kaakaa/config.scm.in
new file mode 100644
index 0000000..2c9e0d2
--- /dev/null
+++ b/kaakaa/config.scm.in
@@ -0,0 +1,27 @@
+;;; kaakaa --- Tiny, security-focused AI agent in Guile
+;;; Copyright © 2026 Arun Isaac <arunisaac@systemreboot.net>
+;;;
+;;; This file is part of kaakaa.
+;;;
+;;; kaakaa is free software: you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation, either version 3 of the License, or
+;;; (at your option) any later version.
+;;;
+;;; kaakaa is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+;;; General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with kaakaa.  If not, see <https://www.gnu.org/licenses/>.
+
+(define-module (kaakaa config)
+  #:export (%project
+            %version))
+
+(define %project
+  "@PROJECT@")
+
+(define %version
+  "@VERSION@")
diff --git a/kaakaa/container.scm b/kaakaa/container.scm
new file mode 100644
index 0000000..e7889bb
--- /dev/null
+++ b/kaakaa/container.scm
@@ -0,0 +1,50 @@
+;;; kaakaa --- Tiny, security-focused AI agent in Guile
+;;; Copyright © 2026 Arun Isaac <arunisaac@systemreboot.net>
+;;;
+;;; This file is part of kaakaa.
+;;;
+;;; kaakaa is free software: you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation, either version 3 of the License, or
+;;; (at your option) any later version.
+;;;
+;;; kaakaa is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+;;; General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with kaakaa.  If not, see <https://www.gnu.org/licenses/>.
+
+(define-module (kaakaa container)
+  #:use-module (rnrs io ports)
+  #:use-module (ice-9 match)
+  #:use-module (gnu build linux-container)
+  #:use-module (guix utils)
+  #:use-module (kaakaa records)
+  #:export (call-with-container*))
+
+(define-public-record-type* (<container-result> container-result container-result?)
+  (fields (output container-result-output)
+          (exit-value container-result-exit-value)))
+
+(define (call-with-container* mounts namespaces thunk)
+  "Run @var{thunk} as a process in a container with @var{mounts} and
+@var{namespaces}, and return a @code{<container-result>} object."
+  (call-with-temporary-directory
+   (lambda (root)
+     (match (pipe)
+       ((in . out)
+        (match (waitpid (run-container root mounts namespaces 1
+                                       (lambda ()
+                                         (close-port in)
+                                         (with-output-to-port out
+                                           ;; TODO: Capture stderr too.
+                                           thunk)
+                                         (close-port out))))
+          ((_ . status)
+           (close-port out)
+           (let ((result (get-string-all in)))
+             (close-port in)
+             (container-result result
+                               (status:exit-val status))))))))))
diff --git a/kaakaa/lens.scm b/kaakaa/lens.scm
new file mode 100644
index 0000000..f5c9370
--- /dev/null
+++ b/kaakaa/lens.scm
@@ -0,0 +1,62 @@
+;;; kaakaa --- Tiny, security-focused AI agent in Guile
+;;; Copyright © 2026 Arun Isaac <arunisaac@systemreboot.net>
+;;;
+;;; This file is part of kaakaa.
+;;;
+;;; kaakaa is free software: you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation, either version 3 of the License, or
+;;; (at your option) any later version.
+;;;
+;;; kaakaa is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+;;; General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with kaakaa.  If not, see <https://www.gnu.org/licenses/>.
+
+(define-module (kaakaa lens)
+  #:use-module (srfi srfi-1)
+  #:use-module (srfi srfi-26)
+  #:use-module (srfi srfi-43)
+  #:use-module (lens)
+  #:export (vector-nth
+            in-json
+            push
+            prepend-over
+            alist-delete-over))
+
+(define (vector-nth n)
+  "Like @code{nth}, but for vectors."
+  (lens (cut vector-ref <> n)
+        (lambda (vec proc)
+          (vector-append (vector-copy vec 0 n)
+                         (vector (proc (vector-ref vec n)))
+                         (vector-copy vec (1+ n))))))
+
+(define in-json
+  (case-lambda
+    "Like @code{in}, but also allow integer components so that it is
+possible to traverse JSON trees."
+    (() (id))
+    ((key . tail)
+     (compose (apply in-json tail)
+              (if (string? key)
+                  (key-ref key)
+                  (vector-nth key))))))
+
+(define (push lens x object)
+  "Cons @var{x} onto the part of @var{object} that @var{lens} focuses
+on."
+  (over lens (cut cons x <>) object))
+
+(define (prepend-over lens lst object)
+  "Prepend @var{lst} to the part of @var{object} that @var{lens} focuses
+on."
+  (over lens (cut append lst <>) object))
+
+(define (alist-delete-over lens key object)
+  "Delete @var{key} from the association list in @var{object} that
+@var{lens} focuses on."
+  (over lens (cut alist-delete key <>) object))
diff --git a/kaakaa/openai.scm b/kaakaa/openai.scm
new file mode 100644
index 0000000..08a7254
--- /dev/null
+++ b/kaakaa/openai.scm
@@ -0,0 +1,79 @@
+;;; kaakaa --- Tiny, security-focused AI agent in Guile
+;;; Copyright © 2026 Arun Isaac <arunisaac@systemreboot.net>
+;;;
+;;; This file is part of kaakaa.
+;;;
+;;; kaakaa is free software: you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation, either version 3 of the License, or
+;;; (at your option) any later version.
+;;;
+;;; kaakaa is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+;;; General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with kaakaa.  If not, see <https://www.gnu.org/licenses/>.
+
+(define-module (kaakaa openai)
+  #:use-module (rnrs conditions)
+  #:use-module (rnrs exceptions)
+  #:use-module (srfi srfi-11)
+  #:use-module (web client)
+  #:use-module (web http)
+  #:use-module (web response)
+  #:use-module (json)
+  #:export (get-api-key
+            openai-query))
+
+;; TODO: URIs must not be operated on using string operations. Replace with a
+;; more principled implementation involving (web uri).
+(define (uri-join base uri)
+  (string-append base uri))
+
+(define* (json-post url #:key headers json)
+  "Send a POST request to @var{url} with @var{json} body and additional
+@var{headers}. The @samp{Content-Type} header is set to @samp{application/json}
+and need not be specified in @var{headers}. Return JSON response."
+  (let-values (((response body)
+                (http-post url
+                           #:headers `((content-type application/json)
+                                       ,@headers)
+                           #:body (scm->json-string json)
+                           #:streaming? #t)))
+    ;; Guile does not consider application/json responses as textual, and does
+    ;; not automatically set the port encoding to UTF-8.
+    (set-port-encoding! body "UTF-8")
+    (case (quotient (response-code response)
+                    100)
+      ((2) (json->scm body))
+      ((4)
+       (raise-exception
+        (condition (make-violation)
+                   (make-message-condition
+                    (string-append "JSON API request failed with client error code "
+                                   (number->string (response-code response)))))))
+      (else
+       (raise-exception
+        (condition (make-error)
+                   (make-message-condition
+                    (string-append "JSON API request failed with code "
+                                   (number->string (response-code response))))))))))
+
+;; Declare the Authorization header as opaque so that Guile doesn't try to mess
+;; with it.
+(declare-opaque-header! "Authorization")
+
+(define (openai-query base-uri api-key model messages tools)
+  "Send a request to the OpenAI completions API and return the JSON response.
+@var{base-uri} is the base URI of the OpenAI-compatible service. @var{api-key}
+is the API key for authentication. @var{model} is a supported LLM model.
+@var{messages} and @var{tools} are respectively lists of JSON messages and tools
+compatible with the OpenAI API specification."
+  (json-post (uri-join base-uri "/api/v1/chat/completions")
+             #:headers `((authorization
+                          . ,(string-append "Bearer " api-key)))
+             #:json `(("model" . ,model)
+                      ("messages" . ,(list->vector messages))
+                      ("tools" . ,(list->vector tools)))))
diff --git a/kaakaa/records.scm b/kaakaa/records.scm
new file mode 100644
index 0000000..7cdac66
--- /dev/null
+++ b/kaakaa/records.scm
@@ -0,0 +1,165 @@
+;;; kaakaa --- Tiny, security-focused AI agent in Guile
+;;; Copyright © 2026 Arun Isaac <arunisaac@systemreboot.net>
+;;;
+;;; This file is part of kaakaa.
+;;;
+;;; kaakaa is free software: you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation, either version 3 of the License, or
+;;; (at your option) any later version.
+;;;
+;;; kaakaa is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+;;; General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with kaakaa.  If not, see <https://www.gnu.org/licenses/>.
+
+(define-module (kaakaa records)
+  #:use-module (rnrs records procedural)
+  #:use-module (srfi srfi-1)
+  #:use-module (srfi srfi-26)
+  #:use-module (ice-9 match)
+  #:use-module (lens)
+  #:export (define-record-type*
+            define-public-record-type*))
+
+(define (make-record-type* record-name make-constructor . fields)
+  "Create a record type with @var{record-name} and @var{fields}.
+@var{make-constructor} is a function that is passed a basic record constructor
+accepting positional arguments and must return the record constructor. Return
+@code{length(fields) + 3} values---the record type descriptor, the record
+constructor, the record predicate and the field accessors.
+
+@var{fields} is a list of field specifiers each of which is of the form
+@code{(field-name accessor-type)}. @var{accessor-type} is either
+@code{'accessor} or @code{'lensed}."
+  (let* ((rtd (make-record-type-descriptor record-name #f #f #f #f
+                                           (list->vector (map (match-lambda
+                                                                ((field-name _)
+                                                                 field-name))
+                                                              fields))))
+         (constructor (record-constructor
+                       (make-record-constructor-descriptor rtd #f #f)))
+         (accessors (map (cut record-accessor rtd <>)
+                         (iota (length fields)))))
+    (apply values
+           rtd
+           (make-constructor constructor)
+           (record-predicate rtd)
+           (map (match-lambda*
+                  ((_ accessor (_ 'accessor))
+                   accessor)
+                  ((index accessor (_ 'lensed))
+                   (lens accessor
+                         (lambda (record proc)
+                           (apply constructor
+                                  (append (map (lambda (accessor)
+                                                 (accessor record))
+                                               (take accessors index))
+                                          (list (proc ((list-ref accessors index)
+                                                       record)))
+                                          (map (lambda (accessor)
+                                                 (accessor record))
+                                               (drop accessors (1+ index)))))))))
+                (iota (length fields))
+                accessors
+                fields))))
+
+(define-syntax define-record-type*
+  (lambda (x)
+    "Define a record type. All fields are immutable and may optionally have lenses as
+accessors.
+
+Lenses are procedures that combine getters and setters into one structure. They
+allow you to conveniently manipulate parts of deeply nested data structures in a
+composable and purely functional way.
+
+Consider the following example record definition:
+@example
+(define-record-type* (<employee> employee employee?)
+  (name employee-name)
+  (age employee-age lensed)
+  (salary employee-salary lensed))
+@end example
+In this example, @code{employee-name} is a regular accessor, while
+@code{employee-age} and @code{employee-salary} are lenses.
+
+@code{employee-name} is a regular accessor. Get with:
+@example
+(employee-name x)
+@end example
+
+@code{employee-age} is a lens. Get with:
+@example
+(focus employee-age x)
+@end example
+
+Functionally update with:
+@example
+(put employee-age 25 x)
+@end example
+
+Record definitions may also optionally specify a @code{make-constructor}
+argument which is passed to @code{make-record-type*}. For example:
+@example
+(define-record-type* (<employee> employee employee?)
+  (lambda (constructor)
+    (lambda* (name #:key age salary)
+      (constructor name age salary)))
+  (fields (name employee-name)
+          (age employee-age lensed)
+          (salary employee-salary lensed)))
+@end example
+"
+    (syntax-case x (fields)
+      ((_ (record-name constructor-name predicate-name)
+          make-constructor
+          (fields field-spec ...))
+       #`(define-values (record-name constructor-name predicate-name
+                                     #,@(map (lambda (x)
+                                               (syntax-case x ()
+                                                 ((_ accessor-name _ ...)
+                                                  #'accessor-name)))
+                                             #'(field-spec ...)))
+           (make-record-type* 'record-name
+                              make-constructor
+                              #,@(map (lambda (x)
+                                        (syntax-case x (lensed)
+                                          ((field-name accessor-name)
+                                           #''(field-name accessor))
+                                          ((field-name accessor-name lensed)
+                                           #''(field-name lensed))))
+                                      #'(field-spec ...)))
+           ))
+      ((_ (record-name constructor-name predicate-name)
+          (fields field-spec ...))
+       #'(define-record-type* (record-name constructor-name predicate-name)
+           identity
+           (fields field-spec ...))))))
+
+(define-syntax define-public-record-type*
+  (lambda (x)
+    "Like @code{define-record-type*}, but also export the constructor, the predicate
+and the accessors."
+    (syntax-case x (fields)
+      ((_ (record-name constructor-name predicate-name)
+          make-constructor
+          (fields field-spec ...))
+       #`(begin
+           (define-record-type* (record-name constructor-name predicate-name)
+             make-constructor
+             (fields field-spec ...))
+           (export constructor-name)
+           (export predicate-name)
+           #,@(map (lambda (x)
+                     (syntax-case x ()
+                       ((_ accessor-name _ ...)
+                        #'(export accessor-name))))
+                   #'(field-spec ...))))
+      ((_ (record-name constructor-name predicate-name)
+          (fields field-spec ...))
+       #'(define-public-record-type* (record-name constructor-name predicate-name)
+           identity
+           (fields field-spec ...))))))
diff --git a/kaakaa/tea.scm b/kaakaa/tea.scm
new file mode 100644
index 0000000..b57e56e
--- /dev/null
+++ b/kaakaa/tea.scm
@@ -0,0 +1,486 @@
+;;; kaakaa --- Tiny, security-focused AI agent in Guile
+;;; Copyright © 2026 Arun Isaac <arunisaac@systemreboot.net>
+;;;
+;;; This file is part of kaakaa.
+;;;
+;;; kaakaa is free software: you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation, either version 3 of the License, or
+;;; (at your option) any later version.
+;;;
+;;; kaakaa is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+;;; General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with kaakaa.  If not, see <https://www.gnu.org/licenses/>.
+
+(define-module (kaakaa tea)
+  #:use-module (rnrs io ports)
+  #:use-module (rnrs records syntactic)
+  #:use-module (srfi srfi-1)
+  #:use-module (srfi srfi-11)
+  #:use-module (srfi srfi-26)
+  #:use-module (ice-9 match)
+  #:use-module (json)
+  #:use-module (lens)
+  #:use-module (kaakaa lens)
+  #:use-module (kaakaa openai)
+  #:use-module (kaakaa records)
+  #:use-module (kaakaa tools)
+  #:use-module (kaakaa utils)
+  #:export (initial-state
+            tea-loop))
+
+(define %tool-allow-once
+  '(("optionId" . "allow-once")
+    ("name" . "Allow once")
+    ("kind" . "allow_once")))
+
+(define %tool-reject-once
+  '(("optionId" . "reject-once")
+    ("name" . "Reject once")
+    ("kind" . "reject_once")))
+
+(define-record-type* (<session> session session?)
+  (lambda (constructor)
+    (lambda* (cwd #:key cancelling? (messages '()) (pending-tool-calls '()))
+      (constructor cwd cancelling? messages pending-tool-calls)))
+  (fields (cwd session-cwd lensed)
+          (cancelling? session-cancelling? lensed)
+          (messages session-messages lensed)
+          (tool-calls session-tool-calls lensed)))
+
+(define-record-type* (<state> state state?)
+  (fields (client-request-id state-client-request-id lensed)
+          (agent-request-id state-agent-request-id lensed)
+          (next-session-id state-next-session-id lensed)
+          ;; Association list mapping agent request IDs to tool calls
+          ;; for which permission is sought
+          (requests-alist state-requests-alist lensed)
+          (sessions state-sessions lensed)))
+
+(define (initial-state)
+  (state #f 0 0 '() '()))
+
+(define-record-type* (<llm-request> llm-request llm-request?)
+  (fields (session-id llm-request-session-id)
+          (messages llm-request-messages)))
+
+(define-record-type* (<llm-response> llm-response llm-response?)
+  (fields (session-id llm-response-session-id)
+          (json llm-response-json)))
+
+(define-record-type* (<acp-message> acp-message acp-message?)
+  (fields (json acp-message-json)))
+
+(define (state-messages session-id)
+  "Return a lens to focus on messages of session with @var{session-id} in
+state."
+  (compose session-messages
+           (key-ref session-id)
+           state-sessions))
+
+(define (state-tool-calls session-id)
+  "Return a lens to focus on tool calls of session with @var{session-id}
+in state."
+  (compose session-tool-calls
+           (key-ref session-id)
+           state-sessions))
+
+(define (state-tool-call tool-call-id session-id)
+  "Return a lens to focus on tool call with @var{tool-call-id} of session
+with @var{session-id} in state."
+  (compose (key-ref tool-call-id)
+           (state-tool-calls session-id)))
+
+(define (state-session-cancelling? session-id)
+  "Return a lens to focus on the @code{cancelling?} flag of session with
+@var{session-id} in state."
+  (compose session-cancelling?
+           (key-ref session-id)
+           state-sessions))
+
+(define (state->llm-request session-id state)
+  "Return an @code{<llm-request>} for session with @var{session-id} in
+@var{state}."
+  (llm-request session-id
+               (map (lambda (message)
+                      ;; Strip out all fields (such as reasoning
+                      ;; fields) other than role, content and
+                      ;; tool_calls.
+                      (filter (match-lambda
+                                ((key . _)
+                                 (member key (list "role" "content"
+                                                   "tool_calls"))))
+                              message))
+                    ;; Reverse because we have been prepending new
+                    ;; messages onto the list.
+                    (reverse (focus (state-messages session-id)
+                                    state)))))
+
+(define (next-state-client-request state request)
+  "Given current @var{state} and a new ACP @var{request}, return the
+next state and a list of effects."
+  (let ((request-id (focus (key-ref "id")
+                           request)))
+    (cond
+     ;; There is a pending request from the client; process it.
+     ((focus (key-ref "method") request)
+      => (match-lambda
+           ("initialize"
+            (values state
+                    (list (acp-message `(("jsonrpc" . "2.0")
+                                         ("id" . ,request-id)
+                                         ("result"
+                                          ("protocolVersion" . 1)
+                                          ("agentCapabilities")
+                                          ("agentInfo"
+                                           ("name" . "kaakaa")
+                                           ("title" . "Kaakaa")
+                                           ("version" . "0.1.0"))
+                                          ("authMethods" . #())))))))
+           ("session/new"
+            (let ((session-id
+                   (string-append "session-"
+                                  (number->string
+                                   (focus state-next-session-id state)))))
+              (values (-> state
+                          ;; Push new session onto list.
+                          (push state-sessions
+                                (cons session-id
+                                      ;; TODO: Check if cwd is an
+                                      ;; absolute path.
+                                      (session (focus (in "params" "cwd")
+                                                      request)))
+                                <>)
+                          ;; Increment next session ID.
+                          (over state-next-session-id
+                                1+
+                                <>))
+                      (list (acp-message `(("jsonrpc" . "2.0")
+                                           ("id" . ,request-id)
+                                           ("result"
+                                            ("sessionId" . ,session-id))))))))
+           ("session/prompt"
+            (let* ((session-id (focus (in "params" "sessionId")
+                                      request))
+                   (state (push (state-messages session-id)
+                                `(("role" . "user")
+                                  ("content" .
+                                   ;; TODO: Filter to only allow
+                                   ;; "text" type content blocks.
+                                   ,(focus (in "params" "prompt")
+                                           request)))
+                                state)))
+              (values state
+                      (list (state->llm-request session-id state)))))
+           ("session/cancel"
+            (let ((session-id (focus (in "params" "sessionId")
+                                     request)))
+              ;; Reset state and end the prompt turn.
+              (values (-> state
+                          (put (state-session-cancelling? session-id)
+                               #f
+                               <>)
+                          (put (state-tool-calls session-id)
+                               '()
+                               <>)
+                          (put state-requests-alist
+                               '()
+                               <>))
+                      (list (acp-message `(("jsonrpc" . "2.0")
+                                           ("id" . ,(focus state-client-request-id
+                                                           state))
+                                           ("result"
+                                            ("stopReason" . "cancelled")))))))))))))
+
+(define (next-state-client-response state response)
+  "Given current @var{state} and a new ACP @var{response}, return the
+next state and a list of effects."
+  (let ((request-id (focus (key-ref "id")
+                           response)))
+    (cond
+     ;; The tool call for this response has been found; process it.
+     ((focus (compose (key-ref request-id)
+                      state-requests-alist)
+             state)
+      => (lambda (tool-call)
+           (let* ((session-id (tool-call-session-id tool-call))
+                  (outcome (focus (in "result" "outcome")
+                                  response))
+                  (outcome-type (focus (key-ref "outcome")
+                                       outcome))
+                  (state
+                   (-> state
+                       ;; Update tool status.
+                       (put (compose tool-call-status
+                                     (state-tool-call (tool-call-id tool-call)
+                                                      session-id))
+                            ;; TODO: Implement other tool permissions.
+                            (cond
+                             ((string=? outcome-type "cancelled")
+                              'cancelled)
+                             ((and (string=? outcome-type "selected")
+                                   (string=? (focus (key-ref "optionId")
+                                                    outcome)
+                                             (focus (key-ref "optionId")
+                                                    %tool-allow-once)))
+                              'approved)
+                             (else 'rejected))
+                            <>)
+                       ;; If the tool call was cancelled, set the
+                       ;; cancelling flag to indicate that a
+                       ;; cancellation is in progress.
+                       (put (state-session-cancelling? session-id)
+                            (string=? outcome-type "cancelled")
+                            <>)
+                       ;; Unregister request corresponding to this
+                       ;; response.
+                       (alist-delete-over state-requests-alist
+                                          request-id
+                                          <>))))
+             (values state
+                     ;; Request tool call evaluation. eval-tool-call
+                     ;; handles cancelled and rejected tool calls
+                     ;; correctly. We don't have to worry about it
+                     ;; here.
+                     (list (focus (state-tool-call (tool-call-id tool-call)
+                                                   (tool-call-session-id tool-call))
+                                  state))))))
+     ;; Client response is stale (it pertains to a request not in
+     ;; requests-alist). Silently ignore it.
+     (else (values state '())))))
+
+(define (next-state-llm-response state response)
+  "Given current @var{state} and a new LLM @var{response}, return the
+next state and a list of effects."
+  (let* ((session-id (llm-response-session-id response))
+         (llm-reply (focus (in-json "choices" 0 "message")
+                           (llm-response-json response)))
+         (tool-calls (cond
+                      ((focus (key-ref "tool_calls")
+                              llm-reply)
+                       => (lambda (json)
+                            (map (cut spec->tool-call
+                                      session-id
+                                      (focus (compose session-cwd
+                                                      (key-ref session-id)
+                                                      state-sessions)
+                                             state)
+                                      <>)
+                                 (vector->list json))))
+                      (else '())))
+         (request-ids (iota (length tool-calls)
+                            (focus state-agent-request-id
+                                   state))))
+    (values (-> state
+                ;; Push LLM response onto messages.
+                (push (state-messages session-id)
+                      llm-reply
+                      <>)
+                ;; Queue new tool calls.
+                (prepend-over (state-tool-calls session-id)
+                              (map (lambda (tool-call)
+                                     (cons (tool-call-id tool-call)
+                                           tool-call))
+                                   tool-calls)
+                              <>)
+                ;; Register this request so we can recall the details
+                ;; later when the response comes in.
+                (prepend-over state-requests-alist
+                              (map cons
+                                   request-ids
+                                   tool-calls)
+                              <>)
+                ;; Bump up agent request ID by the number of IDs used.
+                (over state-agent-request-id
+                      (cut + (length tool-calls) <>)
+                      <>))
+            (map acp-message
+                 (append `( ;; Send LLM's text response.
+                           (("jsonrpc" . "2.0")
+                            ("method" . "session/update")
+                            ("params"
+                             ("sessionId" . ,session-id)
+                             ("update"
+                              ("sessionUpdate" . "agent_message_chunk")
+                              ("content"
+                               ("type" . "text")
+                               ("text" . ,(focus (key-ref "content")
+                                                 llm-reply)))))))
+                         ;; Request permission from the client.
+                         (map (lambda (call request-id)
+                                `(("jsonrpc" . "2.0")
+                                  ("id" . ,request-id)
+                                  ("method" . "session/request_permission")
+                                  ("params"
+                                   ("sessionId" . ,session-id)
+                                   ("toolCall"
+                                    ("toolCallId" . ,(tool-call-id call)))
+                                   ("options" .
+                                    ,(vector %tool-allow-once
+                                             %tool-reject-once)))))
+                              tool-calls
+                              request-ids)
+                         ;; End prompt turn if there are no further
+                         ;; tool calls and a cancellation is not in
+                         ;; progress.
+                         (if (and (null? tool-calls)
+                                  (not (focus (state-session-cancelling? session-id)
+                                              state)))
+                             `((("jsonrpc" . "2.0")
+                                ("id" . ,(focus state-client-request-id
+                                                state))
+                                ("result"
+                                 ("stopReason" . "end_turn"))))
+                             '()))))))
+
+(define (next-state-tool-call-result state result)
+  "Given current @var{state} and a new tool call @var{result}, return the
+next state and a list of effects."
+  (let* ((session-id (tool-call-result-session-id result))
+         (state (-> state
+                    ;; Push tool call result onto messages.
+                    (push (state-messages session-id)
+                          (tool-call-result-json result)
+                          <>)
+                    ;; Delete tool call from session tool call list.
+                    (alist-delete-over (state-tool-calls session-id)
+                                       (tool-call-result-call-id result)
+                                       <>))))
+    (values state
+            ;; Send a notification for each tool call evaluated.
+            (cons (acp-message `(("jsonrpc" . "2.0")
+                                 ("method" . "session/update")
+                                 ("params"
+                                  ("sessionId" . ,session-id)
+                                  ("update"
+                                   ;; TODO: Add locations and
+                                   ;; rawOutput.
+                                   ("sessionUpdate" . "tool_call")
+                                   ("toolCallId" . ,(tool-call-result-call-id result))
+                                   ("title" . ,(tool-call-result-title result))
+                                   ("kind" . ,(tool-call-result-kind result))
+                                   ("status" .
+                                    ,(if (tool-call-result-success? result)
+                                         "completed"
+                                         "failed"))
+                                   ("content"
+                                    ("type" . "content")
+                                    ("content"
+                                     ("type" . "text")
+                                     ("text" . ,(focus (key-ref "content")
+                                                       (tool-call-result-json result)))))
+                                   ("rawInput" . ,(tool-call-result-arguments result))))))
+                  ;; If there are no more tool calls and a
+                  ;; cancellation is not in progress, dispatch to LLM.
+                  (if (and (null? (focus (state-tool-calls session-id)
+                                         state))
+                           (not (focus (state-session-cancelling? session-id)
+                                       state)))
+                      (list (state->llm-request session-id state))
+                      (list))))))
+
+(define (next-state state message)
+  "Given current @var{state} and a new @var{message}, return the next
+state and a list of effects."
+  (cond
+   ((acp-message? message)
+    (let ((json-message (acp-message-json message)))
+      (if (focus (key-ref "result") json-message)
+          ;; message is a response from the client.
+          (next-state-client-response state json-message)
+          ;; message is a request/notification from the client.
+          (let-values (((state effects)
+                        (next-state-client-request state json-message)))
+            (values (cond
+                     ;; message is a request from the client.
+                     ((focus (key-ref "id") json-message)
+                      => (cut put
+                              state-client-request-id
+                              <>
+                              state))
+                     ;; message is a notification from the client.
+                     (else state))
+                    effects)))))
+   ((llm-response? message)
+    (next-state-llm-response state message))
+   ((tool-call-result? message)
+    (next-state-tool-call-result state message))))
+
+(define (tea-loop state llm-base-uri llm-api-key model tools)
+  "Run a @acronym{TEA, The Elm Architecture} loop starting with
+@var{state}.
+
+@var{llm-base-uri} is the base URI of the LLM provider.
+@var{llm-api-key} is the API key to authenticate with the LLM
+provider. @var{model} is the name of the model. @var{tools} is the
+list of tools made available to the LLM. It is an association list
+matching tool names to @code{<tool>} objects."
+  ;; Read a JSON-RPC message, handle it, and loop.
+  (let ((line (get-line (current-input-port))))
+    (unless (eof-object? line)
+      (tea-loop (handle-event (acp-message (json-string->scm line))
+                              state
+                              llm-base-uri
+                              llm-api-key
+                              model
+                              tools)
+                llm-base-uri
+                llm-api-key
+                model
+                tools))))
+
+(define (handle-event event state llm-base-uri llm-api-key model tools)
+  "Handle @var{event} with @var{state} and return a new state.
+
+@var{llm-base-uri}, @var{llm-api-key}, @var{model} and @var{tools} are
+the same as in @code{tea-loop}."
+  (let-values (((state effects)
+                ;; Compute the next state and collect the effects.
+                (next-state state event)))
+    ;; Do the effects.
+    (fold (cut do-effect <> <> llm-base-uri llm-api-key model tools)
+          state
+          effects)))
+
+(define (do-effect effect state llm-base-uri llm-api-key model tools)
+  "Do @var{effect} with @var{state} and return a new state.
+
+@var{llm-base-uri}, @var{llm-api-key}, @var{model} and @var{tools} are
+the same as in @code{tea-loop}."
+  (cond
+   ;; Send message to client, and return the state unchanged.
+   ((acp-message? effect)
+    (display (scm->json-string (acp-message-json effect)))
+    (newline)
+    (flush-output-port (current-output-port))
+    state)
+   ;; Send request to LLM, handle the response, and return the new
+   ;; state.
+   ((llm-request? effect)
+    ;; TODO: Handle network failures in OpenAI query.
+    (handle-event (llm-response (llm-request-session-id effect)
+                                (openai-query llm-base-uri
+                                              llm-api-key
+                                              model
+                                              (llm-request-messages effect)
+                                              (map (match-lambda
+                                                     ((name . tool)
+                                                      (tool->spec name tool)))
+                                                   tools)))
+                  state
+                  llm-base-uri
+                  llm-api-key
+                  model
+                  tools))
+   ;; Evaluate tool, handle the result, and return the new state.
+   ((tool-call? effect)
+    (handle-event (eval-tool-call effect tools)
+                  state
+                  llm-base-uri
+                  llm-api-key
+                  model
+                  tools))))
diff --git a/kaakaa/tools.scm b/kaakaa/tools.scm
new file mode 100644
index 0000000..b490852
--- /dev/null
+++ b/kaakaa/tools.scm
@@ -0,0 +1,256 @@
+;;; kaakaa --- Tiny, security-focused AI agent in Guile
+;;; Copyright © 2026 Arun Isaac <arunisaac@systemreboot.net>
+;;;
+;;; This file is part of kaakaa.
+;;;
+;;; kaakaa is free software: you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation, either version 3 of the License, or
+;;; (at your option) any later version.
+;;;
+;;; kaakaa is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+;;; General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with kaakaa.  If not, see <https://www.gnu.org/licenses/>.
+
+(define-module (kaakaa tools)
+  #:use-module ((rnrs base) #:select (assertion-violation))
+  #:use-module (rnrs conditions)
+  #:use-module (rnrs exceptions)
+  #:use-module (rnrs records syntactic)
+  #:use-module (srfi srfi-1)
+  #:use-module (ice-9 match)
+  #:use-module (gnu build linux-container)
+  #:use-module (gnu system file-systems)
+  #:use-module (json)
+  #:use-module (lens)
+  #:use-module (kaakaa container)
+  #:use-module (kaakaa records)
+  #:use-module (kaakaa utils)
+  #:export (tool->spec
+            spec->tool-call
+            eval-tool-call))
+
+(define (readonly-cwd-only-mappings cwd arguments)
+  (list (file-system-mapping
+          (source cwd)
+          (target source)
+          (writable? #f))))
+
+(define-public-record-type* (<tool> tool tool?)
+  (lambda (constructor)
+    (lambda* (#:key
+              description (parameters '()) proc
+              (container-mappings readonly-cwd-only-mappings)
+              (container-namespaces %namespaces)
+              title kind)
+      (unless description
+        (raise-exception
+         (condition (make-violation)
+                    (make-message-condition "tool requires description"))))
+      (unless proc
+        (raise-exception
+         (condition (make-violation)
+                    (make-message-condition "tool requires proc"))))
+      (constructor description parameters proc
+                   container-mappings container-namespaces title kind)))
+  (fields (description tool-description)
+          ;; Association list mapping parameter names to
+          ;; <tool-parameter> objects.
+          (parameters tool-parameters)
+          (proc tool-proc)
+          (container-mappings tool-container-mappings)
+          (container-namespaces tool-container-namespaces)
+          (title tool-title)
+          (kind tool-kind)))
+
+(define-public-record-type* (<tool-parameter> tool-parameter tool-parameter?)
+  (lambda (constructor)
+    (lambda* (#:key type description (required? #t))
+      (unless type
+        (raise-exception
+         (condition (make-violation)
+                    (make-message-condition "tool parameter requires type"))))
+      (unless description
+        (raise-exception
+         (condition (make-violation)
+                    (make-message-condition "tool parameter requires description"))))
+      (constructor type description required?)))
+  (fields (type tool-parameter-type)
+          (description tool-parameter-description)
+          (required? tool-parameter-required?)))
+
+(define-public-record-type* (<array-type> array-type array-type?)
+  (fields (subtype array-type-subtype)))
+
+(define (tool->spec name tool)
+  "Serialize @var{tool} of @var{name} to OpenAI-compatible JSON spec."
+  `(("type" . "function")
+    ("function"
+     ("name" . ,name)
+     ("description" . ,(tool-description tool))
+     ("parameters"
+      ("type" . "object")
+      ("properties" .
+       ,(map (match-lambda
+               ((name . parameter)
+                ;; TODO: Check if the OpenAI API supports arrays of
+                ;; arrays and other more deeply nested types.
+                (let ((type (tool-parameter-type parameter)))
+                  `(,name
+                    ("description" . ,(tool-parameter-description parameter))
+                    ("type" . ,(if (array-type? type)
+                                   "array"
+                                   type))
+                    ,@(if (array-type? type)
+                          `(("items" . ,(array-type-subtype type)))
+                          '())))))
+             (tool-parameters tool)))
+      ("required" .
+       ,(list->vector
+         (filter-map (match-lambda
+                       ((name . parameter)
+                        (and (tool-parameter-required? parameter)
+                             name)))
+                     (tool-parameters tool))))))))
+
+(define-public-record-type* (<tool-call> tool-call tool-call?)
+  (fields (session-id tool-call-session-id)
+          (session-cwd tool-call-session-cwd)
+          (id tool-call-id)
+          (function tool-call-function)
+          (arguments tool-call-arguments)
+          ;; One of 'approved, 'rejected or 'cancelled
+          (status tool-call-status lensed)))
+
+(define-public-record-type* (<tool-call-result> tool-call-result tool-call-result?)
+  (fields (session-id tool-call-result-session-id)
+          (call-id tool-call-result-call-id)
+          (title tool-call-result-title)
+          (kind tool-call-result-kind)
+          (arguments tool-call-result-arguments)
+          (json tool-call-result-json)
+          (success? tool-call-result-success?)))
+
+(define-condition-type &tool-call-failure &serious
+  tool-call-failure tool-call-failure?
+  (message tool-call-failure-message))
+
+(define (spec->tool-call session-id session-cwd spec)
+  "Deserialize JSON tool call @var{spec} into a @code{<tool-call>}
+object. @var{session-id} and @var{session-cwd} are the ID and current working
+directory of the session the tool call pertains to."
+  ;; TODO: Assert that type is function, and do more sanitization.
+  (tool-call session-id
+             session-cwd
+             (focus (key-ref "id")
+                    spec)
+             (focus (in "function" "name")
+                    spec)
+             ;; The arguments may be invalid JSON. So, we don't deserialize
+             ;; right away.
+             (focus (in "function" "arguments")
+                    spec)
+             'pending-approval))
+
+(define (eval-tool-call tool-call tools)
+  "Evaluate @var{tool-call} and return a @code{<tool-call-result>}
+object. @var{tools} is an association list mapping the names of all
+available tools to their respective @code{<tool>} objects."
+  (cond
+   ((focus (key-ref (tool-call-function tool-call))
+           tools)
+    => (lambda (tool)
+         (case (focus tool-call-status tool-call)
+           ;; User approved tool call.
+           ((approved)
+            (guard (c ((tool-call-failure? c)
+                       (tool-call-result (tool-call-session-id tool-call)
+                                         (tool-call-id tool-call)
+                                         #f
+                                         #f
+                                         (tool-call-arguments tool-call)
+                                         `(("role" . "tool")
+                                           ("tool_call_id" . ,(tool-call-id tool-call))
+                                           ("content" . ,(tool-call-failure-message c)))
+                                         #f)))
+              (let* ((args
+                      ;; Deserialize arguments checking for valid JSON.
+                      (guard (c (else
+                                 (raise-exception
+                                  (tool-call-failure
+                                   "Error: Arguments are not valid JSON"))))
+                        (json-string->scm (tool-call-arguments tool-call))))
+                     (filtered-args
+                      ;; Only pick out valid arguments, and error out if any
+                      ;; required arguments are missing.
+                      (alist->plist
+                       (filter-map (match-lambda
+                                     ((arg-name . parameter)
+                                      (cond
+                                       ((assoc arg-name args)
+                                        => identity)
+                                       (else
+                                        (and (tool-parameter-required? parameter)
+                                             (raise-exception
+                                              (tool-call-failure
+                                               (string-append "Error: Missing required argument "
+                                                              arg-name))))))))
+                                   (tool-parameters tool))))
+                     ;; Actually evaluate tool call.
+                     (tool-result
+                      (call-with-container*
+                          (map file-system-mapping->bind-mount
+                               ((tool-container-mappings tool)
+                                (tool-call-session-cwd tool-call)
+                                filtered-args))
+                          (tool-container-namespaces tool)
+                        (lambda ()
+                          (chdir (tool-call-session-cwd tool-call))
+                          (apply (tool-proc tool)
+                                 filtered-args)))))
+                ;; Build result.
+                (tool-call-result (tool-call-session-id tool-call)
+                                  (tool-call-id tool-call)
+                                  (apply (tool-title tool) filtered-args)
+                                  (apply (tool-kind tool) filtered-args)
+                                  (tool-call-arguments tool-call)
+                                  `(("role" . "tool")
+                                    ("tool_call_id" . ,(tool-call-id tool-call))
+                                    ("content" . ,(container-result-output tool-result)))
+                                  (zero? (container-result-exit-value tool-result))))))
+           ;; User cancelled or rejected tool call.
+           ((cancelled rejected)
+            (tool-call-result (tool-call-session-id tool-call)
+                              (tool-call-id tool-call)
+                              #f
+                              #f
+                              (tool-call-arguments tool-call)
+                              `(("role" . "tool")
+                                ("tool_call_id" . ,(tool-call-id tool-call))
+                                ("content" .
+                                 ,(case (focus tool-call-status tool-call)
+                                    ((rejected)
+                                     "Error: User denied permission for this tool call")
+                                    ((cancelled)
+                                     "Error: User cancelled this tool call"))))
+                              #f))
+           (else
+            (assertion-violation (focus tool-call-status tool-call)
+                                 "Invalid tool call status")))))
+   (else
+    (tool-call-result (tool-call-session-id tool-call)
+                      (tool-call-id tool-call)
+                      #f
+                      #f
+                      (tool-call-arguments tool-call)
+                      `(("role" . "tool")
+                        ("tool_call_id" . ,(tool-call-id tool-call))
+                        ("content" .
+                         ,(string-append "Error: Function of name "
+                                         (tool-call-function tool-call)
+                                         " not found")))
+                      #f))))
diff --git a/kaakaa/tools/base.scm b/kaakaa/tools/base.scm
new file mode 100644
index 0000000..38aed17
--- /dev/null
+++ b/kaakaa/tools/base.scm
@@ -0,0 +1,54 @@
+;;; kaakaa --- Tiny, security-focused AI agent in Guile
+;;; Copyright © 2026 Arun Isaac <arunisaac@systemreboot.net>
+;;;
+;;; This file is part of kaakaa.
+;;;
+;;; kaakaa is free software: you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation, either version 3 of the License, or
+;;; (at your option) any later version.
+;;;
+;;; kaakaa is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+;;; General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with kaakaa.  If not, see <https://www.gnu.org/licenses/>.
+
+(define-module (kaakaa tools base)
+  #:use-module (rnrs io ports)
+  #:use-module (guix build utils)
+  #:use-module (kaakaa tools)
+  #:export (%list-files
+            %base-tools))
+
+(define %read
+  (tool #:description "Read file"
+        #:parameters `(("path" . ,(tool-parameter
+                                   #:type "string"
+                                   #:description "File path to read"
+                                   #:required? #t)))
+        #:proc (lambda* (#:key path)
+                 ;; TODO: Handle non-existent files.
+                 (display (call-with-input-file path
+                            get-string-all)))
+        #:title (const "Read file")
+        #:kind (const "read")))
+
+(define %list-files
+  (tool #:description "List files in current directory"
+        #:parameters (list)
+        #:proc (lambda _
+                 (for-each (lambda (file)
+                             (display file)
+                             (newline))
+                           (find-files (getcwd))))
+        #:title (const "List files")
+        #:kind (const "read")))
+
+(define %base-tools
+  `(("read" . ,%read)
+    ("list-files" . ,%list-files)))
+
+;; TODO: Implement write, grep and find.
diff --git a/kaakaa/utils.scm b/kaakaa/utils.scm
new file mode 100644
index 0000000..5677af2
--- /dev/null
+++ b/kaakaa/utils.scm
@@ -0,0 +1,67 @@
+;;; kaakaa --- Tiny, security-focused AI agent in Guile
+;;; Copyright © 2026 Arun Isaac <arunisaac@systemreboot.net>
+;;;
+;;; This file is part of kaakaa.
+;;;
+;;; kaakaa is free software: you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation, either version 3 of the License, or
+;;; (at your option) any later version.
+;;;
+;;; kaakaa is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+;;; General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with kaakaa.  If not, see <https://www.gnu.org/licenses/>.
+
+(define-module (kaakaa utils)
+  #:use-module (srfi srfi-1)
+  #:use-module (srfi srfi-26)
+  #:use-module (ice-9 match)
+  #:use-module (ice-9 popen)
+  #:export (->
+            alist->plist
+            call-with-input-pipe))
+
+(define (->-helper x . procs)
+  "Thread @var{x} through @var{procs}."
+  (match procs
+    (() x)
+    ((head tail ...)
+     (apply ->-helper (head x) tail))))
+
+(define-syntax-rule (-> x (proc ...) ...)
+  "Thread @var{x} through @var{procs}.
+
+For example:
+(-> 1
+    (1+ <>)
+    (* 2 <>)
+    (expt <> 2))
+=> 16"
+  (->-helper x (cut proc ...) ...))
+
+(define (alist->plist alist)
+  "Convert association list @var{alist} to a property list. Keys in
+@var{alist} are converted to keywords."
+  (append-map (match-lambda
+                ((key . value)
+                 (list (symbol->keyword (string->symbol key))
+                       value)))
+              alist))
+
+(define (call-with-input-pipe command proc)
+  "Call @var{proc} with input pipe to @var{command}. @var{command} is a
+list of program arguments."
+  (match command
+    ((prog args ...)
+     (let ((port #f))
+       (dynamic-wind
+         (lambda ()
+           (set! port (apply open-pipe* OPEN_READ prog args)))
+         (cut proc port)
+         (lambda ()
+           (unless (zero? (close-pipe port))
+             (error "Command invocation failed" command))))))))
diff --git a/manifest.scm b/manifest.scm
new file mode 100644
index 0000000..f0fe58e
--- /dev/null
+++ b/manifest.scm
@@ -0,0 +1,16 @@
+(use-modules ((gnu packages guile-xyz) #:select (guile-ares-rs))
+             ((gnu packages task-management) #:select (git-bug))
+             ((kaakaa-package) #:select (kaakaa))
+             (srfi srfi-1))
+
+(define (manifest-cons* . args)
+  "ARGS is of the form (PACKAGES ... ONTO-MANIFEST). Return a manifest
+with PACKAGES and all packages in ONTO-MANIFEST."
+  (let ((packages (drop-right args 1))
+        (onto-manifest (last args)))
+    (manifest (append (map package->manifest-entry packages)
+                      (manifest-entries onto-manifest)))))
+
+(manifest-cons* git-bug
+                guile-ares-rs
+                (package->development-manifest kaakaa))
diff --git a/pre-inst-env b/pre-inst-env
new file mode 100755
index 0000000..b01b5ed
--- /dev/null
+++ b/pre-inst-env
@@ -0,0 +1,38 @@
+#! /usr/bin/env guile
+!#
+;;; kaakaa --- Tiny, security-focused AI agent in Guile
+;;; Copyright © 2026 Arun Isaac <arunisaac@systemreboot.net>
+;;;
+;;; This file is part of kaakaa.
+;;;
+;;; kaakaa is free software: you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation, either version 3 of the License, or
+;;; (at your option) any later version.
+;;;
+;;; kaakaa is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+;;; General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with kaakaa.  If not, see <https://www.gnu.org/licenses/>.
+
+(use-modules (ice-9 match))
+
+(define (prepend-path-env! name . values)
+  (setenv name (string-join (append values
+                                    (if (getenv name)
+                                        (string-split (getenv name) #\:)
+                                        '()))
+                            ":")))
+
+(define %source-dir (dirname (current-filename)))
+
+(prepend-path-env! "GUILE_LOAD_PATH" %source-dir)
+(prepend-path-env! "GUILE_LOAD_COMPILED_PATH" %source-dir)
+(prepend-path-env! "PATH" (string-append %source-dir "/bin"))
+
+(match (command-line)
+  ((_ command args ...)
+   (apply execlp command command args)))